Premature birth is defined either as the same as preterm
birth, or the birth of a baby before the developing organs are mature
enough to allow normal postnatal survival.
Premature infants are at greater risk for short and long term complications, including disabilities and impediments in growth and mental development.
Significant progress has been made in the care of premature infants, but
not in reducing the prevalence of preterm birth.
Preterm birth is among the top causes of death in infants worldwide.
Infants who were born prematurely are colloquially referred to as "preemies".
Also, vaginal bleeding in the third trimester, heavy pressure in the pelvis, or abdominal or back pain could be indicators that a preterm birth is about to occur.
A watery discharge from the vagina may indicate premature rupture of the membranes that surround the baby. While the rupture of the membranes may not be followed by labor, usually delivery is indicated as infection (chorioamnionitis) is a serious threat to both fetus and mother.
In some cases the cervix dilates prematurely without pain or perceived contractions, so that the mother may not have warning signs until very late in the birthing process.
A new mother holds her premature baby at Kapiolani Medical Center NICU in Honolulu, Hawaii
Labor is a complex process involving many factors. Four different pathways have been identified that can result in preterm birth and have considerable evidence: precocious fetal endocrine activation, uterine overdistension (placental abruption), decidual bleeding, and intrauterine inflammation/infection.
Activation of one or more of these pathways may happen gradually over weeks, even months. From a practical point a number of factors have been identified that are associated with preterm birth, however, an association does not establish causality.
Maternal height and weight can also play a role. Further, in the US and the UK, black women have preterm birth rates of 15–18%, more than double than that of the white population.
This discrepancy is not seen in comparison to Asian or Hispanic immigrants and remains unexplained.
Pregnancy interval makes a difference as women with a 6 months span or less between pregnancies have a two-fold increase in preterm birth.
Studies on type of work and physical activity have given conflicting results, but it is opined that stressful conditions, hard labor, and long hours are probably linked to preterm birth.
A history of spontaneous (i.e., miscarriage) or surgical abortion has been associated with a small increase in the risk of preterm birth, with an increased risk with increased number of abortions, although it is unclear whether the increase is caused by the abortion or by confounding risk factors (e.g., socioeconomic status).
Increased risk has not been shown in women who terminated their pregnancies medically.Pregnancies that are unwanted or unintended are also a risk factor for preterm birth.
Adequate maternal nutrition is important. Women with a low BMI are at increased risk for preterm birth.
Further, women with poor nutritional status may also be deficient in vitamins and minerals. Adequate nutrition is critical for fetal development and a diet low in saturated fat and cholesterol may help reduce the risk of a preterm delivery.
Obesity does not directly lead to preterm birth; however, it is associated with diabetes and hypertension which are risk factors by themselves.
Women with a previous preterm birth are at higher risk for a recurrence at a rate of 15–50% depending on number of previous events and their timing.
To some degree those individuals may have underlying conditions (i.e. uterine malformation, hypertension, diabetes) that persist.
Marital status is associated with risk for preterm birth. A study of 25,373 pregnancies in Finland revealed that unmarried mothers had more preterm deliveries than married mothers (P=0.001).
Pregnancy outside of marriage was associated overall with a 20% increase in total adverse outcomes, even at a time when Finland provided free maternity care.
A study in Quebec of 720,586 births from 1990-97 revealed less risk of preterm birth for infants with legally married mothers, compared with those with common law wed or unwed parents.
Genetic make-up is a factor in the causality of preterm birth. An intra- and transgenerational increase in the risk of preterm delivery has been demonstrated.
No single gene has been identified, and it appears with the complexity of the labor initiation, that numerous polymorphic genetic interactions are possible.
Subfertility is associated with preterm birth. Couples who have tried more than 1 year versus those who have tried less than 1 year before achieving a spontaneous conception have an adjusted odds ratio of 1.35 (95% confidence interval 1.22-1.50) of preterm birth.
Pregnancies after IVF confers a greater risk of preterm birth than spontaneous conceptions after more than 1 year of trying, with an adjusted odds ratio of 1.55 (95% CI 1.30-1.85).
Triplets and more are even more endangered. The use of fertility medication that stimulates the ovary to release multiple eggs and of IVF with embryo transfer of multiple embryos has been implicated as an important factor in preterm birth. Maternal medical conditions increase the risk of preterm birth, and often labor has to be induced for medical reasons; such conditions include high blood pressure, pre-eclampsia, maternal diabetes, asthma, thyroid disease, and heart disease.
In a number of women anatomical issues prevent the baby from being carried to term. Some women have a weak or short cervix (the strongest predictor of premature birth)
The cervix may also have been compromised by previous cervical conization or loop excision. In women with uterine malformations the capacity of the uterus to hold the growing pregnancy may be limited and preterm labor ensues.
Women with vaginal bleeding during pregnancy are at higher risk for preterm birth. While bleeding in the third trimester may be a sign of placenta previa or placental abruption – conditions that occur frequently preterm – even earlier bleeding that is not caused by these two conditions is linked to a higher preterm birth rate.
Women with abnormal amounts of amniotic fluid, whether too much (polyhydramnios) or too little (oligohydramnios), are also at risk.
The mental status of the women is of significance. Anxiety and depression have been linked to preterm birth.
Finally, the use of tobacco, cocaine, and excessive alcohol during pregnancy also increases the chance of preterm delivery. Tobacco is the most commonly abused drug during pregnancy and also contributes significantly to low birth weight delivery.
Babies with birth defects are at higher risk of being born preterm.
Presence of anti-thyroid antibodies is associated with an increased risk preterm birth with an odds ratio of 1.9 and 95% confidence interval of 1.1–3.5.
A 2004 systematic review of 30 studies on the association between intimate partner violence and birth outcomes concluded that preterm birth and other adverse outcomes, including death, are higher among abused pregnant women than among non-abused women.
The Nigerian cultural method of abdominal massage has been shown to result in 19% preterm birth among women in Nigeria, plus many other adverse outcomes for the mother and baby.
This ought not be confused with massage conducted by a fully trained and licensed massage therapist or by significant others trained to provide massage during pregnancy, which has been shown to have numerous positive results during pregnancy, including the reduction of preterm birth, less depression, lower cortisol, and reduced anxiety.
Endotoxins released by microorganisms and cytokines stimulate deciduas responses including the release of prostaglandins which may stimulate uterine contractions.
Further the decidual response may include release of matrix-degrading enzymes that weaken fetal membranes leading to premature rupture. Intrauterine infection appears to be a chronic process.
Typical organisms identified in the uterus before rupture of the membranes are genital Mycoplasma spp and specifically Ureaplasma urealyticum.
Micro-organisms may reach the decidua in a number of ways, ascending, hematogeneous, iatrogenic by a procedure, or retrograde through the fallopian tubes.
From the deciduas they may reach the space between the amnion and chorion, the amniotic fluid, and finally the fetus.
A chorioamnionitis also may lead to sepsis of the mother. Fetal infection not only is linked to preterm birth but to significant long-term handicap including cerebral palsy.
It has been reported that asymptomatic colonization of the decidua occurs in up to 70% of women at term using a DNA probe suggesting that the presence of micro-organism alone may be insufficient to initiate the infectious response. Bacterial vaginosis has been linked to preterm birth raising the risk by a factor of 1.5 – 3.
As the condition is more prevalent in black women in the US and the UK, it has been suggested to be an explanation for the higher rate of preterm birth in this population.
It is opined that bacterial vaginosis before or during pregnancy may affect the decidual inflammatory response that leads to preterm birth.
A number of maternal bacterial infections are associated with preterm birth including pyelonephritis, asymptomatic bacteriuria, pneumonia, and appendicitis. Also periodontal disease has been shown repeatedly to be linked to preterm birth.
In contrast, viral infections, unless accompanied by a significant febrile response, are considered not to be a major factor in relation to preterm birth.
Many women experience false labor (not leading to cervical shortening and effacement) and are falsely labeled to be in preterm labor.
The study of preterm birth has been hampered by the difficulty in distinguishing between "true" preterm labor and false labor. These new tests are used to identify women at risk for preterm birth.
A positive test indicates an increased risk of preterm birth, and a negative test has a high predictive value.
It has been shown that only 1% of women in questionable cases of preterm labor delivered within the next week when the test was negative.
A short cervix preterm is undesirable: At 24 weeks gestation a cervix length of less than 25 mm defines a risk group for preterm birth. Further, the shorter the cervix the greater the risk.
It also has been helpful to use ultrasonography in women with preterm contractions, as those whose cervix length exceeds 30 mm are unlikely to deliver within the next week.
Increasingly primary interventions that are directed at all women, and secondary intervention that reduce existing risks are looked upon as measures that need to be developed and implemented to prevent the health problems of premature infants and children.
Many countries have established specific programs to protect pregnant women from hazardous and night-shift work, and to provide them with time for prenatal visits and paid pregnancy-leave.
The EUROPOP study showed that preterm birth is not related to type of employment, but to prolonged work (over 42 hours per week) or prolonged standing (over 6 hours per day). Also, night work has been linked to preterm birth.
Health policies that take these findings into account can be expected to reduce the rate of preterm birth.
Avoidance of weight extremes and good nutritional support are important. Although a study failed to show that multivitamin preparation taken prior to conception reduces the risk of preterm birth, preconceptional intake of folic acid is recommended to reduce birth defects.
There is significant evidence that long term (> one year) use of folic acid supplement preconceptionally may reduce premature birth. Reducing smoking is expected to benefit pregnant women and their offspring.
Calcium supplementation as well as supplemental intake of C and E vitamins could not be shown to reduce preterm birth rates.
Different strategies are used in the administration of prenatal care, and future studies need to determine if the focus should be on screening for high risk women, or widened support for low-risk women, or to what degree these approaches should be merged.
While periodontal infection has been linked with preterm birth, randomized trials have not shown that periodontal care during pregnancy reduces preterm birth rates.
Self-monitoring vaginal pH followed by yogurt treatment or clindamycin treatment if the pH was too high all seem to be effective at reducing the risk of preterm birth.
Patients with certain uterine anomalies may have a surgical correction (i.e. removal of a uterine septum), and those with certain medical problems can be helped by optimizing medical therapies prior to conception, be it for asthma, diabetes, hypertension and others.
Interestingly, even if agents such as calcium or antioxidants were able to reduce preeclampsia, a resulting decrease in preterm birth was not observed.
Also, increasing medical care by more frequent visits and more education has not shown a reduction in preterm birth rates.
Use of nutritional supplements such as omega-3 polyunsaturated fatty acids is based on the observation that populations who have a high intake of such agents are at low risk for preterm birth, presumably as these agents inhibit production of proinflammatory cytokines. A randomized trial showed a significant decline in preterm birth rates, and further studies are in the making.
However, progesterone is not effective in all populations, as a study involving twin gestations failed to see any benefit.
Numerous studies have been performed to assess the value of cervical cerclage and the procedure appears helpful primarily for women with a short cervix and a history of preterm birth.
Instead of a prophylactic cerclage, women at risk can be monitored during pregnancy by sonography, and when shortening of the cervix is observed, the cerclage can be performed.
However, no matter how careful you are spontaneous preterm birth can still occur. Know your body and see your doctor immediately if you notice any sudden changes or experience early contractions.
Preterm-premature babies ("preemies" or "premmies") have an increased risk of death in the first year of life (infant mortality), with most of that occurring in the first month of life (neonatal mortality). Worldwide, prematurity accounts for 10% of neonatal mortality, or around 500,000 deaths per year.
In the U.S. where many infections and other causes of neonatal death have been markedly reduced, prematurity is the leading cause of neonatal mortality at 25%.
Prematurely born infants are also at greater risk for having subsequent serious chronic health problems as discussed below.
The earliest gestational age at which the infant has at least a 50% chance of survival is referred to as the limit of viability. As NICU care has improved over the last 40 years, viability has reduced to approximately 24 weeks, although rare survivors have been documented as early as 21 weeks.
This date is controversial, as gestation in the case reported was measured from the known date of conception (by IVF) rather than, as usual, the date of the mother's last menstrual period, making gestation appear two weeks less than if calculated by the conventional method in this case.
As risk of brain damage and developmental delay is significant at that threshold even if the infant survives, there are ethical controversies over the aggressiveness of the care rendered to such infants. The limit of viability has also become a factor in the abortion debate.
White matter connectivity between the frontal and posterior brain regions are critical in learning to identify patterns in language.
Preterm children are at a greater risk for having poor connectivity between these areas leading to learning disabilities.
Cardiovascular complications may arise from the failure of the ductus arteriosus to close after birth: patent ductus arteriosus (PDA).
34 percent were mildly disabled and 20 percent had no disabilities, while 12 percent had disabling cerebral palsy.
While treatments to arrest early labor where there is progressive cervical dilatation and effacement will not be effective to gain sufficient time to allow the fetus to grow and mature further, it may defer delivery sufficiently to allow the mother to be brought to a specialized center that is equipped and staffed to handle preterm deliveries.
Centers for the care of women with preterm delivery are usually staffed by maternal-fetal specialists and highly trained staff and linked to neonatal intensive care units.
In a hospital setting women are hydrated via intravenous infusion (as dehydration can lead to premature uterine contractions).
Premature infants are at greater risk for short and long term complications, including disabilities and impediments in growth and mental development.
Preterm birth is among the top causes of death in infants worldwide.
Infants who were born prematurely are colloquially referred to as "preemies".
Signs and symptoms of preterm labor
The main categories of causes of preterm birth are preterm labor induction and spontaneous preterm labor. Signs and symptoms of preterm labor include four or more uterine contractions in one hour. In contrast to false labor, true labor is accompanied by cervical dilatation and effacement.Also, vaginal bleeding in the third trimester, heavy pressure in the pelvis, or abdominal or back pain could be indicators that a preterm birth is about to occur.
A watery discharge from the vagina may indicate premature rupture of the membranes that surround the baby. While the rupture of the membranes may not be followed by labor, usually delivery is indicated as infection (chorioamnionitis) is a serious threat to both fetus and mother.
In some cases the cervix dilates prematurely without pain or perceived contractions, so that the mother may not have warning signs until very late in the birthing process.
Risk factors
As the cause of labor still remains elusive, the exact cause of preterm birth is also unsolved. In fact, the cause of 50% of preterm births is never determined.Labor is a complex process involving many factors. Four different pathways have been identified that can result in preterm birth and have considerable evidence: precocious fetal endocrine activation, uterine overdistension (placental abruption), decidual bleeding, and intrauterine inflammation/infection.
Activation of one or more of these pathways may happen gradually over weeks, even months. From a practical point a number of factors have been identified that are associated with preterm birth, however, an association does not establish causality.
Maternal background
A number of factors have been identified that are linked to a higher risk of a preterm birth: age at the upper and lower end of the reproductive years, be it more than 35 or less than 18 years of age.Maternal height and weight can also play a role. Further, in the US and the UK, black women have preterm birth rates of 15–18%, more than double than that of the white population.
This discrepancy is not seen in comparison to Asian or Hispanic immigrants and remains unexplained.
Pregnancy interval makes a difference as women with a 6 months span or less between pregnancies have a two-fold increase in preterm birth.
Studies on type of work and physical activity have given conflicting results, but it is opined that stressful conditions, hard labor, and long hours are probably linked to preterm birth.
A history of spontaneous (i.e., miscarriage) or surgical abortion has been associated with a small increase in the risk of preterm birth, with an increased risk with increased number of abortions, although it is unclear whether the increase is caused by the abortion or by confounding risk factors (e.g., socioeconomic status).
Increased risk has not been shown in women who terminated their pregnancies medically.Pregnancies that are unwanted or unintended are also a risk factor for preterm birth.
Adequate maternal nutrition is important. Women with a low BMI are at increased risk for preterm birth.
Further, women with poor nutritional status may also be deficient in vitamins and minerals. Adequate nutrition is critical for fetal development and a diet low in saturated fat and cholesterol may help reduce the risk of a preterm delivery.
Obesity does not directly lead to preterm birth; however, it is associated with diabetes and hypertension which are risk factors by themselves.
Women with a previous preterm birth are at higher risk for a recurrence at a rate of 15–50% depending on number of previous events and their timing.
To some degree those individuals may have underlying conditions (i.e. uterine malformation, hypertension, diabetes) that persist.
Marital status is associated with risk for preterm birth. A study of 25,373 pregnancies in Finland revealed that unmarried mothers had more preterm deliveries than married mothers (P=0.001).
Pregnancy outside of marriage was associated overall with a 20% increase in total adverse outcomes, even at a time when Finland provided free maternity care.
A study in Quebec of 720,586 births from 1990-97 revealed less risk of preterm birth for infants with legally married mothers, compared with those with common law wed or unwed parents.
Genetic make-up is a factor in the causality of preterm birth. An intra- and transgenerational increase in the risk of preterm delivery has been demonstrated.
No single gene has been identified, and it appears with the complexity of the labor initiation, that numerous polymorphic genetic interactions are possible.
Subfertility is associated with preterm birth. Couples who have tried more than 1 year versus those who have tried less than 1 year before achieving a spontaneous conception have an adjusted odds ratio of 1.35 (95% confidence interval 1.22-1.50) of preterm birth.
Pregnancies after IVF confers a greater risk of preterm birth than spontaneous conceptions after more than 1 year of trying, with an adjusted odds ratio of 1.55 (95% CI 1.30-1.85).
Factors during pregnancy
Multiple pregnancies (twins, triplets, etc.) are a significant factor in preterm birth. The March of Dimes Multicenter Prematurity and Prevention Study found that 54% of twins were delivered preterm vs. 9.6% of singleton births.Triplets and more are even more endangered. The use of fertility medication that stimulates the ovary to release multiple eggs and of IVF with embryo transfer of multiple embryos has been implicated as an important factor in preterm birth. Maternal medical conditions increase the risk of preterm birth, and often labor has to be induced for medical reasons; such conditions include high blood pressure, pre-eclampsia, maternal diabetes, asthma, thyroid disease, and heart disease.
In a number of women anatomical issues prevent the baby from being carried to term. Some women have a weak or short cervix (the strongest predictor of premature birth)
The cervix may also have been compromised by previous cervical conization or loop excision. In women with uterine malformations the capacity of the uterus to hold the growing pregnancy may be limited and preterm labor ensues.
Women with vaginal bleeding during pregnancy are at higher risk for preterm birth. While bleeding in the third trimester may be a sign of placenta previa or placental abruption – conditions that occur frequently preterm – even earlier bleeding that is not caused by these two conditions is linked to a higher preterm birth rate.
Women with abnormal amounts of amniotic fluid, whether too much (polyhydramnios) or too little (oligohydramnios), are also at risk.
The mental status of the women is of significance. Anxiety and depression have been linked to preterm birth.
Finally, the use of tobacco, cocaine, and excessive alcohol during pregnancy also increases the chance of preterm delivery. Tobacco is the most commonly abused drug during pregnancy and also contributes significantly to low birth weight delivery.
Babies with birth defects are at higher risk of being born preterm.
Presence of anti-thyroid antibodies is associated with an increased risk preterm birth with an odds ratio of 1.9 and 95% confidence interval of 1.1–3.5.
A 2004 systematic review of 30 studies on the association between intimate partner violence and birth outcomes concluded that preterm birth and other adverse outcomes, including death, are higher among abused pregnant women than among non-abused women.
The Nigerian cultural method of abdominal massage has been shown to result in 19% preterm birth among women in Nigeria, plus many other adverse outcomes for the mother and baby.
This ought not be confused with massage conducted by a fully trained and licensed massage therapist or by significant others trained to provide massage during pregnancy, which has been shown to have numerous positive results during pregnancy, including the reduction of preterm birth, less depression, lower cortisol, and reduced anxiety.
Infection
Infections play a major role in the genesis of preterm birth and may account for 25–40% of events. The frequency of infection in preterm birth is inversely related to the gestational age.Endotoxins released by microorganisms and cytokines stimulate deciduas responses including the release of prostaglandins which may stimulate uterine contractions.
Further the decidual response may include release of matrix-degrading enzymes that weaken fetal membranes leading to premature rupture. Intrauterine infection appears to be a chronic process.
Typical organisms identified in the uterus before rupture of the membranes are genital Mycoplasma spp and specifically Ureaplasma urealyticum.
Micro-organisms may reach the decidua in a number of ways, ascending, hematogeneous, iatrogenic by a procedure, or retrograde through the fallopian tubes.
From the deciduas they may reach the space between the amnion and chorion, the amniotic fluid, and finally the fetus.
A chorioamnionitis also may lead to sepsis of the mother. Fetal infection not only is linked to preterm birth but to significant long-term handicap including cerebral palsy.
It has been reported that asymptomatic colonization of the decidua occurs in up to 70% of women at term using a DNA probe suggesting that the presence of micro-organism alone may be insufficient to initiate the infectious response. Bacterial vaginosis has been linked to preterm birth raising the risk by a factor of 1.5 – 3.
As the condition is more prevalent in black women in the US and the UK, it has been suggested to be an explanation for the higher rate of preterm birth in this population.
It is opined that bacterial vaginosis before or during pregnancy may affect the decidual inflammatory response that leads to preterm birth.
A number of maternal bacterial infections are associated with preterm birth including pyelonephritis, asymptomatic bacteriuria, pneumonia, and appendicitis. Also periodontal disease has been shown repeatedly to be linked to preterm birth.
In contrast, viral infections, unless accompanied by a significant febrile response, are considered not to be a major factor in relation to preterm birth.
Diagnosis
A helpful clinical test should predict a high risk for preterm birth during the early and middle part of the third trimester, when their impact is significant.Many women experience false labor (not leading to cervical shortening and effacement) and are falsely labeled to be in preterm labor.
The study of preterm birth has been hampered by the difficulty in distinguishing between "true" preterm labor and false labor. These new tests are used to identify women at risk for preterm birth.
Fetal fibronectin
Fetal fibronectin has become the most important biomarker—the presence of this glycoprotein in the cervical or vaginal secretions indicates that the border between the chorion and deciduas has been disrupted.A positive test indicates an increased risk of preterm birth, and a negative test has a high predictive value.
It has been shown that only 1% of women in questionable cases of preterm labor delivered within the next week when the test was negative.
Ultrasonography of the cervix
Obstetric ultrasound has become useful in the assessment of the cervix in women at risk for premature delivery.A short cervix preterm is undesirable: At 24 weeks gestation a cervix length of less than 25 mm defines a risk group for preterm birth. Further, the shorter the cervix the greater the risk.
It also has been helpful to use ultrasonography in women with preterm contractions, as those whose cervix length exceeds 30 mm are unlikely to deliver within the next week.
Prevention
Historically efforts have been primarily aimed to improve survival and health of preterm infants (tertiary intervention). Such efforts, however, have not reduced the incidence of preterm birth.Increasingly primary interventions that are directed at all women, and secondary intervention that reduce existing risks are looked upon as measures that need to be developed and implemented to prevent the health problems of premature infants and children.
Preconceptional
Adoption of specific professional policies can immediately reduce risk of preterm birth as the experience in assisted reproduction has shown when the number of embryos during embryo transfer were limited.Many countries have established specific programs to protect pregnant women from hazardous and night-shift work, and to provide them with time for prenatal visits and paid pregnancy-leave.
The EUROPOP study showed that preterm birth is not related to type of employment, but to prolonged work (over 42 hours per week) or prolonged standing (over 6 hours per day). Also, night work has been linked to preterm birth.
Health policies that take these findings into account can be expected to reduce the rate of preterm birth.
Avoidance of weight extremes and good nutritional support are important. Although a study failed to show that multivitamin preparation taken prior to conception reduces the risk of preterm birth, preconceptional intake of folic acid is recommended to reduce birth defects.
There is significant evidence that long term (> one year) use of folic acid supplement preconceptionally may reduce premature birth. Reducing smoking is expected to benefit pregnant women and their offspring.
During pregnancy
Interventions that should have been initiated prior to pregnancy can still be instituted during pregnancy, including nutritional adjustments, use of vitamin supplements, and smoking cessation.Calcium supplementation as well as supplemental intake of C and E vitamins could not be shown to reduce preterm birth rates.
Different strategies are used in the administration of prenatal care, and future studies need to determine if the focus should be on screening for high risk women, or widened support for low-risk women, or to what degree these approaches should be merged.
While periodontal infection has been linked with preterm birth, randomized trials have not shown that periodontal care during pregnancy reduces preterm birth rates.
Screening of low risk women
Screening for asymptomatic bacteriuria followed by appropriate treatment reduces pyelonephritis and reduces the risk of preterm birth.[53] Extensive studies have been carried out to determine if other forms of screening in low-risk women followed by appropriate intervention are beneficial, including: Screening for and treatment of Ureaplasma urealyticum, group B streptococcus, Trichomonas vaginalis, and bacterial vaginosis did not reduce the rate of preterm birth.[44] Routine ultrasound examination of the length of the cervix identifies patients at risk, but cerclage is not proven useful, and the application of a progesterone is under study.[44] Screening for the presence of fibronectin in vaginal secretions is not recommended at this time in women at low risk.Self-care
Self-care methods to reduce the risk of preterm birth include proper nutrition, avoiding stress, seeking appropriate medical care, avoiding infections, and the control of preterm birth risk factors (e.g. working long hours while standing on feet, carbon monoxide exposure, domestic abuse, and other factors).Self-monitoring vaginal pH followed by yogurt treatment or clindamycin treatment if the pH was too high all seem to be effective at reducing the risk of preterm birth.
Secondary (reducing existing risks)
Women are identified to be at increased risk for preterm birth on the basis of their past obstetrical history or the presence of known risk factors. Preconception intervention can be helpful in selected patients in a number of ways.Patients with certain uterine anomalies may have a surgical correction (i.e. removal of a uterine septum), and those with certain medical problems can be helped by optimizing medical therapies prior to conception, be it for asthma, diabetes, hypertension and others.
During pregnancy
Reducing indicated preterm birth
A number of agents have been studied for secondary prevention of indicated preterm birth. Trials using low-dose aspirin, fish oil, vitamin C and E, and calcium to reduce preeclampsia demonstrated some reduction in preterm birth only when low-dose aspirin was used.Interestingly, even if agents such as calcium or antioxidants were able to reduce preeclampsia, a resulting decrease in preterm birth was not observed.
Reducing spontaneous preterm birth
Reduction in maternal activity – pelvic rest, limited work, bed rest – is frequently recommended although there is no clear proof of its efficacy.Also, increasing medical care by more frequent visits and more education has not shown a reduction in preterm birth rates.
Use of nutritional supplements such as omega-3 polyunsaturated fatty acids is based on the observation that populations who have a high intake of such agents are at low risk for preterm birth, presumably as these agents inhibit production of proinflammatory cytokines. A randomized trial showed a significant decline in preterm birth rates, and further studies are in the making.
- Antibiotics
- Progesterone
However, progesterone is not effective in all populations, as a study involving twin gestations failed to see any benefit.
- Cervical cerclage
Numerous studies have been performed to assess the value of cervical cerclage and the procedure appears helpful primarily for women with a short cervix and a history of preterm birth.
Instead of a prophylactic cerclage, women at risk can be monitored during pregnancy by sonography, and when shortening of the cervix is observed, the cerclage can be performed.
However, no matter how careful you are spontaneous preterm birth can still occur. Know your body and see your doctor immediately if you notice any sudden changes or experience early contractions.
Complications
Mortality and morbidity
The shorter the term of pregnancy, the greater the risks of mortality and morbidity for the baby primarily due to the related prematurity.Preterm-premature babies ("preemies" or "premmies") have an increased risk of death in the first year of life (infant mortality), with most of that occurring in the first month of life (neonatal mortality). Worldwide, prematurity accounts for 10% of neonatal mortality, or around 500,000 deaths per year.
In the U.S. where many infections and other causes of neonatal death have been markedly reduced, prematurity is the leading cause of neonatal mortality at 25%.
Prematurely born infants are also at greater risk for having subsequent serious chronic health problems as discussed below.
The earliest gestational age at which the infant has at least a 50% chance of survival is referred to as the limit of viability. As NICU care has improved over the last 40 years, viability has reduced to approximately 24 weeks, although rare survivors have been documented as early as 21 weeks.
This date is controversial, as gestation in the case reported was measured from the known date of conception (by IVF) rather than, as usual, the date of the mother's last menstrual period, making gestation appear two weeks less than if calculated by the conventional method in this case.
As risk of brain damage and developmental delay is significant at that threshold even if the infant survives, there are ethical controversies over the aggressiveness of the care rendered to such infants. The limit of viability has also become a factor in the abortion debate.
Specific risks for the preterm neonate
Preterm infants usually show physical signs of prematurity in reverse proportion to the gestational age. As a result they are at risk for numerous medical problems affecting different organ systems.- Neurological problems include apnea of prematurity, hypoxic-ischemic encephalopathy (HIE), retinopathy of prematurity (ROP), developmental disability, transient hyperammonemia of the newborn, cerebral palsy and intraventricular hemorrhage, the latter affecting 25 percent of babies born preterm, usually before 32 weeks of pregnancy.
- Mild brain bleeds usually leave no or few lasting complications, but severe bleeds often result in brain damage or even death. Neurodevelopmental problems have been linked to lack of maternal thyroid hormones, at a time when their own thyroid is unable to meet postnatal needs.
White matter connectivity between the frontal and posterior brain regions are critical in learning to identify patterns in language.
Preterm children are at a greater risk for having poor connectivity between these areas leading to learning disabilities.
Cardiovascular complications may arise from the failure of the ductus arteriosus to close after birth: patent ductus arteriosus (PDA).
- Respiratory problems are common, specifically the respiratory distress syndrome (RDS or IRDS) (previously called hyaline membrane disease). Another problem can be chronic lung disease (previously called bronchopulmonary dysplasia or BPD).
- Gastrointestinal and metabolic issues can arise from hypoglycemia, feeding difficulties, rickets of prematurity, hypocalcemia, inguinal hernia, and necrotizing enterocolitis (NEC).
- Hematologic complications include anemia of prematurity, thrombocytopenia, and hyperbilirubinemia (jaundice) that can lead to kernicterus.
- Infection, including sepsis, pneumonia, and urinary tract infection
34 percent were mildly disabled and 20 percent had no disabilities, while 12 percent had disabling cerebral palsy.
Management
Tertiary interventions are aimed at women who are about to go into preterm labor, or rupture the membranes or bleed preterm. The use of the fibronectin test and ultrasonography improves the diagnostic accuracy and reduces false-positive diagnosis.While treatments to arrest early labor where there is progressive cervical dilatation and effacement will not be effective to gain sufficient time to allow the fetus to grow and mature further, it may defer delivery sufficiently to allow the mother to be brought to a specialized center that is equipped and staffed to handle preterm deliveries.
Centers for the care of women with preterm delivery are usually staffed by maternal-fetal specialists and highly trained staff and linked to neonatal intensive care units.
In a hospital setting women are hydrated via intravenous infusion (as dehydration can lead to premature uterine contractions).
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