by Melinda Beck
Wall Street Journal
Wall Street Journal
This time of year, some hospitals see a small uptick in baby deliveries thanks to families eager to fit the blessed event in around holiday plans or in time to claim a tax deduction. Conventional wisdom has long held that inducing labor or having a Caesarean section a bit early posed little risk, since after 34 weeks gestation, all the baby has to do was grow.
But new research shows that those last weeks of pregnancy are more important than once thought for brain, lung and liver development. And there may be lasting consequences for babies born at 34 to 36 weeks, now called "late preterm." A study in the American Journal of Obstetrics and Gynecology in October calculated that for each week a baby stayed in the womb between 32 and 39 weeks, there is a 23% decrease in problems such as respiratory distress, jaundice, seizures, temperature instability and brain hemorrhages.
A study of nearly 15,000 children in the Journal of Pediatrics in July found that those born between 32 and 36 weeks had lower reading and math scores in first grade than babies who went to full term. New research also suggests that late preterm infants are at higher risk for mild cognitive and behavioral problems and may have lower I.Q.s than those who go full term.
What's more, experts warn that a fetus's estimated age may be off by as much as two weeks either way, meaning that a baby thought to be 36 weeks along might be only 34.
The American College of Obstetricians and Gynecologists, the American Academy of Pediatrics and the March of Dimes are now urging obstetricians not to deliver babies before 39 weeks unless there is a medical reason to do so.
Why do doctors agree to deliver a baby early when there's no medical reason? Some cite pressure from parents. "'I'm tired of being pregnant. My fingers are swollen. My mother-in-law is coming' -- we hear that all the time," says Laura E. Riley, medical director of labor and delivery at Massachusetts General Hospital. "But there are 25 other patients waiting, and saying 'no' can take 45 minutes, so sometimes we cave."
There's also a perception that delivering early by c-section is safer for the baby, even though it means major surgery for the mom. "The idea is that somehow, if you're in complete control of the delivery, then only good things will happen. But that's categorically wrong. The baby and the uterus know best," says F. Sessions Cole, director of newborn medicine at St. Louis Children's Hospital. He explains that a complex series of events occurs in late pregnancy to prepare the baby to survive outside the womb: The fetus acquires fat needed to maintain body temperature; the liver matures enough to eliminate a toxin called bilirubin from the body; and the lungs get ready to exchange oxygen as soon as the umbilical cord is clamped. Disrupting any of those steps can result in brain damage and other problems. In addition, the squeezing of the uterus during labor stimulates the baby and the placenta to make steroid hormones that help this last phase of lung maturation -- and that's missed if the mother never goes into labor.
Bonnie - why do we continue to "push the envelope," assuming that we, instead of nature, know best?
But new research shows that those last weeks of pregnancy are more important than once thought for brain, lung and liver development. And there may be lasting consequences for babies born at 34 to 36 weeks, now called "late preterm." A study in the American Journal of Obstetrics and Gynecology in October calculated that for each week a baby stayed in the womb between 32 and 39 weeks, there is a 23% decrease in problems such as respiratory distress, jaundice, seizures, temperature instability and brain hemorrhages.
A study of nearly 15,000 children in the Journal of Pediatrics in July found that those born between 32 and 36 weeks had lower reading and math scores in first grade than babies who went to full term. New research also suggests that late preterm infants are at higher risk for mild cognitive and behavioral problems and may have lower I.Q.s than those who go full term.
What's more, experts warn that a fetus's estimated age may be off by as much as two weeks either way, meaning that a baby thought to be 36 weeks along might be only 34.
The American College of Obstetricians and Gynecologists, the American Academy of Pediatrics and the March of Dimes are now urging obstetricians not to deliver babies before 39 weeks unless there is a medical reason to do so.
Why do doctors agree to deliver a baby early when there's no medical reason? Some cite pressure from parents. "'I'm tired of being pregnant. My fingers are swollen. My mother-in-law is coming' -- we hear that all the time," says Laura E. Riley, medical director of labor and delivery at Massachusetts General Hospital. "But there are 25 other patients waiting, and saying 'no' can take 45 minutes, so sometimes we cave."
There's also a perception that delivering early by c-section is safer for the baby, even though it means major surgery for the mom. "The idea is that somehow, if you're in complete control of the delivery, then only good things will happen. But that's categorically wrong. The baby and the uterus know best," says F. Sessions Cole, director of newborn medicine at St. Louis Children's Hospital. He explains that a complex series of events occurs in late pregnancy to prepare the baby to survive outside the womb: The fetus acquires fat needed to maintain body temperature; the liver matures enough to eliminate a toxin called bilirubin from the body; and the lungs get ready to exchange oxygen as soon as the umbilical cord is clamped. Disrupting any of those steps can result in brain damage and other problems. In addition, the squeezing of the uterus during labor stimulates the baby and the placenta to make steroid hormones that help this last phase of lung maturation -- and that's missed if the mother never goes into labor.
Bonnie - why do we continue to "push the envelope," assuming that we, instead of nature, know best?
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