Will you deliver early?
A textbook pregnancy lasts 40 weeks, but a pregnancy is considered to be "full term" between 38 and 42 weeks. Babies born earlier or later than that have a higher risk of complications. Twins have a 60 percent chance of being born before that time, with the average being 35 weeks. Twins often have a low birth weight, not just because of their premature birth but also because of growth restrictions caused by sharing the uterus with a brother or sister and twin-to-twin transfusion syndrome (TTTS) as well in some babies.
Twins' tendency to be born early may not be totally without reason. Research suggests that twins who share one placenta may be exposed to the same risks singletons experience after 42 weeks of pregnancy. The placenta stops working properly earlier, and may be calcified. There is no guaranteed way to prevent going into labor early, whether you are expecting twins or only one baby. Still, some doctors suggest reducing physical activity and turning the final weeks of a twin pregnancy into a restful period in which you do as little as possible. Staying properly hydrated may play a role in preventing preterm labor in twins too, according to some doctors at least. Don't let the lack of scientific evidence stop you, as dehydration is bad for everyone, whether it causes labor or not.
Twin vaginal birth
Many people mistakenly believe that it is always safer for twins to be born by cesarean section. In the United States, a country with a very high c-section rate, more than half of all twin births are vaginal! Women who are pregnant with twins should discuss their options and preferences for labor and delivery in detail with their healthcare team. Cesarean sections are recommended in certain cases, which we will get too later. In many twin pregnancies, vaginal delivery is a perfectly safe possibility. Research suggests that 40 percent of twins are both vertex, or head down, by the time they are ready to be born. This is the ideal situation, and unless you are dealing with other complicating factors, you will be a great candidate for vaginal birth if your babies are head down. If baby A, the first baby, is vertex and baby B is breech (butt or feet down), that is also a position from which most doctors will be happy to attempt a vaginal birth. With a twin vaginal birth, your medical team is more likely to ask you to have epidural anesthesia just in case you will need an emergency c-section. Continuous fetal monitoring will almost certainly be a part of a twin vaginal delivery.
Scheduled cesarean section for twins
Pregnancies in which both twins are breech, or baby A is breech, are more risky. Your doctor will almost certainly strongly recommend or "require" you to have a cesarean section if you are in this situation. If your babies share a placenta or your placenta is near your cervix, a c-section will also be recommended in most cases. The same goers for women who have already had a c-section before. A scheduled cesarean section is safer, and offers the patient more freedom of choice, than an emergency c-section. There are quite a few stories going around about obstetricians/gynecologists, or hospitals, having a "policy" to do c-sections only for twin births.
If this happens to you and there is no real medical reason to move right to a c-section rather than at least attempting a vaginal delivery, remember that you almost always have the chance to seek a second opinion from another doctor, either at the same or another hospital. Some mothers prefer scheduled elective c-sections for their twin delivery, even if they could have attempted to have a vaginal birth. Again, discussing the risks and advantages with your doctor is the best plan of action. Keep in mind that c-section recovery tends to take longer than recovering from a vaginal birth, something that matters all the more when you have two newborns!