Cheryl Madden knows a thing or two about those last few frustrating ready-to-pop weeks of pregnancy. Her first two kids, daughter Addison (now six) and son Paxton (now four), were content to stay where they were for a full 10 or 11 days past their due dates. While Madden didn’t love the late-term heartburn, she was pretty philosophical about it all. “My attitude was they were where they needed to be, and they would come out when they were ready,” says the Winnipeg mom.
Madden’s take is the popular one. “There is a body of evidence and literature that shows there is very important development, particularly brain development, that happens in the last few weeks of pregnancy, and it happens better in the uterus than outside,” says George Carson, an OB/GYN in Regina. “When I’m talking to my patients, I say pregnancy is like baking: You don’t want to take the baby out until he or she is done.” He adds that although Canadian guidelines are less clear-cut than those in the US, in practice, “done” or full-term is considered to be 39 weeks or beyond, assuming a normal pregnancy in which both the mom and the baby are safe and healthy. (The American Congress of Obstetricians and Gynecologists changed its definition of a full-term baby from 37 weeks to 39 in 2013.) If your labour starts naturally at 37 or 38 weeks, don’t fret: In a typical pregnancy, it just means your baby is ready to be born. (If you have a condition like pre-eclampsia or significant bleeding during pregnancy, an induction or C-section could happen before 39 weeks.)
To help keep you motivated while you wait, here are five amazing things your baby is doing late in your pregnancy.
1. Growing a bigger brain A baby’sbrain almost doubles in size between 35 and 39 weeks. During the final stages of pregnancy, your baby is forming brain connections and pathways that are important for learning, movement and coordination after she’s born.
2. Developing better lungs “The thinking used to be that lungs were fully developed by 37 weeks, but now there’s research to show this development is still continuing until birth and beyond,” says Shâdé Chatrath, a registered midwife in Toronto. Between weeks 24 and 28, your baby produces a substance called surfactant, which prevents the air sacs in his lungs from sticking together once he takes that first gulp of air. A University of Buffalo study of 30,000 births found that babies born at 37 to 38 weeks were twice as likely to need help breathing through ventilation and a dose of surfactant compared with babies born at 39 to 41 weeks. (Babies born before 37 weeks are usually given surfactant through a ventilator to get it to their lungs.)
3. Fine-tuning the liver Like the lungs and the brain, the liver develops up to 39 weeks. One of the liver’s big jobs is to filter out a substance called bilirubin (pigment from red blood cells) from the baby’s bloodstream. Babies born before 38 weeks may not be able to process bilirubin as quickly as full-term babies, putting them at higher risk for jaundice after birth.
4. Losing body hair and making poop The fine, downy hair that covers babies in utero is called lanugo, and it helps vernix (a creamy or waxy white substance) stick, keeping them warm and protecting their skin from amniotic fluid while they’re inside. Many babies shed much of the hair into the amniotic fluid shortly before birth. And yes, your baby is constantly swallowing that fluid, which also contains bile, waste products and cells that have been shed. Those many gulps end up in his intestines, where it becomes meconium, a newborn’s dark, tar-like first bowel movement.
5. Plumping up At week 35, your baby gains about half a pound a week. This layer of fat helps him keep warm after he’s born. His chest becomes more formed and prominent, and in boys, testicles continue to descend.
If Chatrath’s clients are feeling “over it” in the final weeks of pregnancy, she reminds them to trust their bodies and why it’s important for the baby to cook a little longer. The happy result: “Women feel more empowered and confident in their bodies’ abilities to grow and deliver babies safely.”
Who’s the Boss? A 2015 study in the Journal of Clinical Investigation conducted by researchers at UT Southwestern Medical Centre in Texas suggests that as a baby’s lungs develop, they release two proteins into the amniotic fluid. These proteins trigger an inflammatory response in the uterus that kicks off labour. That’s right: In a lot of deliveries, baby likely does decide when it’s go time.