The average single baby measures about 51cm (20in) from head to foot, and weighs between 2.5kg and 3kg at birth. However, twins tend to be a bit lighter than this when they're born.
Your twins' organs are fully developed and in place, although their lungs are still maturing. If you go into labour prematurely, you may be offered steroids to help your babies breathe after the birth. Your twins may also need a little extra care in their first days and weeks.
Around now, one of your twins will gradually move down into your pelvis, ready to be born. This will clear some much-needed space in the upper part of your womb (uterus). You may find that your breathing suddenly becomes a bit easier again!
Your twins are looking like newborns now. Most of the downy hair (lanugo) and waxy white substance (vernix caseosa) that covered their bodies has gone. They're also shedding the top layer of their skin, as new skin grows beneath it. All these substances float in the amniotic fluid, which was once clear and is now a pale straw colour.
Your twins will continue to swallow amniotic fluid, and some of it will stay in their bowels until after they're born. It will come out of them as a sticky, dark substance called meconium. This will be your babies' first poo.
You may already have experienced light, irregular Braxton Hicks contractions. These could become much more frequent as your body prepares for labour and birth.
How your baby is born
A 3D animated look at the stages of labour from contractions to birth. More inside pregnancy videos
Note: every pregnancy is different. This page is designed to give a general idea of how twins grow in the womb.
Last reviewed July 2020
