You’ve seen the pregnancy calendars (40 weeks’ worth). You might have estimated your due date. But just as 95 percent of all singleton births fail to fall on their due date, you shouldn’t count on your twins' births hitting the bull’s-eye either.
If your pregnancy ends up going past your due date, your practitioner might induce depending on how you’re progressing. It’s a good idea to have an “end-game” discussion with your practitioner long before, since many doctors differ on how they typically handle the latter stages of twin pregnancies.
More typical for multiples, however, is that the pregnancy will end up being shorter than full-term — and many multiple moms-to-be find themselves in a race with the calendar, trying to maintain the pregnancy long enough to ensure healthy outcomes for the babies.
Here's what you can expect, what's considered full-term for twins and what timetable milestones to hit when you're pregnant with twins.
What's considered full-term for twins?
Full-term for twins is the same as full-term for singleton babies, technically: 39 weeks pregnant. But if your twins are born at 37 weeks, that's as close to actual full-term as many twins get. At that point, they have full lung maturity and should be able to leave the hospital within a few days of delivery.
Will my twins be born early?
More than half of twins and other multiples are born early, before 37 weeks of pregnancy, so there's a 50/50 chance that yours will arrive before their due date too. Many twins are born between 35 and 37 weeks.
The reason? Being pregnant with twins ups your chances of preterm labor and complications including preeclampsia, problems with the placenta (like placenta previa), gestational diabetes and twin-to-twin transfusion syndrome that would likely result in an early delivery.
More About Being Pregnant with Multiples
A lot depends on what types of twins you're carrying. Twins who share amniotic sacs and/or placentas can sometimes face more complications and will usually be delivered earlier than twins with separate amniotic sacs and/or placentas.
Twin pregnancy timetable milestones
The first major milestone in a twin pregnancy is 24 weeks. Advances in medical care have improved the odds for even younger babies, but babies born at 24 weeks will likely spend a few months in the neonatal intensive care unit (NICU) until they can breathe on their own and maintain their body temperature, among other things.
The second milestone is 28 weeks, when viability skyrockets. Ninety percent of babies who make it to this stage of gestation survive. Long-term complications — including cerebral palsy, vision and breathing problems — are still a possibility, however.
A third milestone in a twin pregnancy is 32 weeks to 34 weeks. Babies born then generally have an excellent chance of survival, without any major long-term complications, though they might not have full lung maturity and will need to spend time in the NICU.
Some babies born at this stage may require oxygen to help them breathe, while others may need to be fed through a nasogastric tube (which runs through the nose into the stomach). “Super-twins” (triplets or more) almost always spend time in a NICU, but if you can get past that 32-week mark, chances are excellent that the babies will be healthy.
What tests will my twins have to have before they're born?
To ensure that your pregnancy — and your babies’ growth and maturity — are on the right track, your practitioner will probably order a barrage of tests as the end of your pregnancy approaches (generally at around the 32-week mark, when all is well).
You can expect nonstress tests, biophysical profiles and/or even late-stage amniocentesis to check for lung maturity and other indicators of how the fetuses are developing.
Depending on the test results, your practitioner may decide to deliver your babies early or leave them cooking in the womb a little longer.
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