It was not long ago that a pregnancy lasting 37 weeks was considered full term.
Some women mistakenly think that the only thing a baby does during the last weeks of pregnancy is gain weight, making labor and delivery more difficult.
New research, however, is changing doctors’ and women’s expectations about pregnancy. These studies compare the health of full-term babies born at 39 weeks of pregnancy to those born just a few weeks too soon. We now know that the last few weeks of pregnancy are crucial to a baby’s health because many vital organs, including the brain and lungs, are still developing. Premature birth is the leading cause of newborn death and babies born just a few weeks early have an increased risk of death and are more likely to be hospitalized than those born full term.
Preterm birth is a birth before the 37th week of pregnancy. A full-term pregnancy lasts 37 to 41 weeks, but a delivery should not be scheduled before 39 weeks unless there is a medial reason. When babies are born early—even just a few weeks early—they face a range of potential health problems, including breathing problems and difficulty feeding and digesting.
During the last weeks of pregnancy, babies’ brains continue to develop. In fact, a baby’s brain at 35 weeks of pregnancy weighs only two-thirds of what it will weight at 39 to 40 weeks. The lungs, liver, ears and eyes continue to mature as well. This is also when babies learn to suck and swallow. The baby fat gained helps retain body heat and provide warmth.
If a pregnancy is healthy, it is best to wait for labor to begin on its own. Although the decision to do a cesarean birth (also called a c-section) should be made by a woman and her provider, the March of Dimes advises against elective c-sections before 39 completed weeks of pregnancy. The March of Dimes and obstetric provider groups urge women who are considering scheduling a delivery to wait until at least 39 weeks of pregnancy.
Scheduling a delivery at the right time can be difficult. Sometimes it’s hard to know just when a woman became pregnant. Even with an ultrasound, a due date can be off by as much as two weeks. If a woman schedules to induce labor or a c-section and her due date is off by a week or two, her baby may be born too early.
Health officials here in Florida and in other states are working closely with March of Dimes staff and volunteers on the “Healthy Babies are Worth the Wait” educational campaign, which urges hospitals, health care providers, and patients to avoid medically unnecessary elective deliveries before 39 weeks of pregnancy.
In Florida, the March of Dimes supports hospital-based quality improvement efforts with grant funds, including grants to the University of South Florida to support the Florida Perinatal Quality Collaborative, and with funding to the Florida Association of Healthy Start Coalitions to improve awareness among women about the message, “if your pregnancy is healthy, it’s best to wait for labor to begin on its own.”
Of course, some women may not have a choice about when to have their baby. If there are problems with the pregnancy or the baby’s health, the baby may need to be delivered early. But women who have a choice, and are planning to schedule their baby’s birth, should wait until at least 39 weeks.
A health care provider is the best source of information throughout a pregnancy. The provider knows the woman’s medical history and current condition. She has followed the pregnancy and is best suited to create a health care plan based upon each woman’s specific needs.
The March of Dimes “Healthy Babies are Worth the Wait” program at www.marchofdimes.com/39weeks reminds women that if a pregnancy is healthy, it’s best to wait for labor to begin on its own, rather than scheduling a delivery. A new CineMama app, available for free through iTunes from the March of Dimes, encourages women to have a full-term pregnancy by allowing them to create a time-lapse video of their pregnancy while getting health tips along the way.
Most moms can’t wait to meet their baby face to face. But getting to at least 39 weeks gives the baby the time needed to grow.
By Dr. Siobhan Dolan, M.D., M.P.H., medical advisor to the March of Dimes
Siobhan Dolan, M.D., M.P.H., is an obstetrician, gynecologist and clinical geneticist who serves as a medical advisor to March of Dimes. Dr. Dolan is an Associate Professor in the Department of Obstetrics & Gynecology and Women’s Health at the Albert Einstein College of Medicine and an attending physician in the Division of Reproductive Genetics at Montefiore Medical Center, the University Hospital for Einstein, in New York City. She is also on the faculty of the Human Genetics Program at Sarah Lawrence College in Bronxville, N.Y. Board-certified in both OB/GYN and Clinical Genetics, Dr. Dolan graduated magna cum laude with honors from Brown University and received her medical degree from Harvard Medical School. She did her residency in OB/GYN at the New York Hospital-Cornell Medical Center and Yale-New Haven Hospital and her fellowship in clinical genetics at the Albert Einstein College of Medicine. She received a master’s degree in public health from Columbia University.
Dr. Dolan maintains her clinical practice serving women and families in the Bronx. Her research interests focus on the integration of genetics into maternal child health, specifically looking at ways to apply advances in genetics and genomics to improve the health of mothers and babies and prevent birth defects and preterm birth. The mother of three teenagers, she lives with her family in Westchester County, N.Y.