When Your Due Date Passes: What Comes Next?

Your due date has come and gone. Here's how passing the 40-week mark can affect your pregnancy and delivery.

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Ask any mom whose pregnancy went into extra innings: Right around your due date, the phone calls, emails and texts start coming: "Is anything happening?" "What does the doctor say?" "Wellll????" Playing the waiting game during the last few weeks of pregnancy is hard, but it becomes especially difficult when 40 weeks turn into 41 . . . or 42. But the first thing to know is this: Your due date is just an estimate. In fact, only 5 percent of babies are born on theirs.

"No woman should feel nervous or anxious if she's still pregnant after her due date," says Alex C. Vidaeff, M.D., M.P.H., a maternal-fetal medicine researcher and practitioner at the University of Texas Medical School at Houston. "Due dates can be off by a week in either direction." Sometimes, even two weeks! Despite that fact, many women get hung up on those dates and feel distress when they come and go, Vidaeff adds.

In the first trimester, your due date is calculated by adding 40 weeks (280 days) to the first day of your last menstrual period, then synched with ultrasound images that date the age of the embryo or fetus. But the result is just an educated "guesstimate." "You might really be 39 weeks when you think you're at 40," says Vidaeff, adding that pregnancy length is, in many cases, genetically determined.

Going into overtime The strict medical definition of "post-term" (aka "post-date") is a pregnancy that goes beyond 42 weeks. However, recent research has shown that delivery after 40 weeks may come with certain risks, and OB-GYNs have responded in kind. "We now change our clinical practices at 40 weeks to prevent potential complications in both mom and baby," says Carri R. Warshak, M.D., an assistant professor in the department of maternal-fetal medicine at the University of Cincinnati.

At the 40-week mark, your doctor or midwife will become more vigilant about monitoring the baby. Post-term infants are at higher risk for problems with glucose metabolism, which can lead to excessive birth weight, and for inhaling meconium (fecal waste); this can cause breathing problems or infection at birth. Amniotic fluid levels can drop, and after 42 weeks, the placenta may not work as well as it did earlier.

Your caregiver will regularly check your amniotic fluid level, the baby's heart rate and his estimated weight, which increases significantly from 40 to 42 weeks. "If the fetus weighs more than 8 pounds, 13 ounces, you may have difficulty pushing during labor, and using a forceps or vacuum may be necessary for delivery," says Warshak.

When baby needs a nudge After 39 or 40 weeks, it's sometimes best to deliver sooner rather than later: Studies have shown that newborn admissions to the neonatal intensive care unit (NICU) increase slightly when a pregnancy lasts 40 to 42 weeks. And stillbirth, though still rare, becomes a concern: At 40 weeks, the risk is 2 to 3 per 1,000 babies; at 42 weeks, it's 4 to 7 per 1,000. If labor hasn't started spontaneously, you'll probably be induced at 41 weeks—at the latest. "If your cervix has started to dilate, odds are in your favor for a successful induction," Warshak says. Translation: You won't end up having a Cesarean section.

Whether or not you'll be induced depends on your own health, the status of your cervix and the baby's well-being as determined by a non-invasive procedure called fetal non-stress testing. The conditions inside your uterus after your due date may also stress the baby during labor and vaginal delivery. As a result, Warshak says, "Even if your cervix is at 8 centimeters and labor is progressing, we'll do a C-section if the baby is not tolerating labor well."

The midwife philosophy Midwives tend to wait a little longer than OB-GYNs do. "In our practice, we wait until 42 weeks for women to go into labor naturally," says Joanne Hasman, C.N.M., a certified nurse-midwife at Special Beginnings Birth and Women's Center in Arnold, Md. "If they don't by then, we schedule an induction at our hospital. We also try natural methods and refer women for acupuncture, reflexology or reiki."

At 40 to 41 weeks, if your cervix is dilated at least 2 centimeters, the midwives in Hasman's practice perform what's called a "cervical sweep," using a finger to separate the cervix from the amniotic sac. This can sometimes kick-start labor. "If the woman is really ready [to go into labor], I'll see her back here in 24 to 36 hours," Hasman says.

The C-section question
An ongoing concern has been whether induction, as opposed to what's known as expectant management (waiting for labor to start spontaneously while monitoring the mother's and baby's well-being), might lead to a higher risk for emergency Cesarean section, and studies have been conflicting. But a new Danish study of more than 230,000 women found that inducing labor from week 39 to week 41 is not connected with higher C-section rates compared with waiting for labor to begin spontaneously or inducing labor later.

Playing the waiting game
Backaches, heartburn, hemorrhoids—at 40 weeks all you want to do is hold your baby in your arms. Here are a few tips to help you cope:

■ MAKE GOOD USE OF YOUR EXTRA TIME Sleep. Finish the nursery. Stock your larder with ready-made meals. Address birth announcements and thank-you notes.

■ CREATE A BLOG OR VOICEMAIL MESSAGE Keep family and friends up-to-date with a daily blog entry, such as: "Just visited the doc, who said everything's fine." Record a new voicemail with an upbeat message: "No, baby's not here yet. Thankfully, we're all healthy. Keep checking this message for daily updates!"

■ SHUN DIY LABOR STARTERS "There are no home remedies that reliably and safely initiate labor," says maternal-fetal medicine specialist Carri R. Warshak, M.D. "If there were, we'd use them in the hospital." Castor oil can make you sick and dehydrated. Spicy foods can give you heartburn. And, she says, no good studies back the claims that sex or exercise can trigger labor.

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