The average singleton baby is about 51cm (20in) long from head to toe and weighs approximately 3.4kg (7.5 lb) at birth. However, anything between 2.5kg (5.5lb) and 3.8kg (8.4lb) is a healthy weight for newborns. Twins tend to be lighter than singleton babies. This is because they grow more slowly during the last month of pregnancy. Around half of twins are born by the end of 36 weeks, which is considered to be normal for twins.
One of your twins will gradually move into your pelvic cavity, which is protected by your pelvic bones. This will clear some much-needed space in the upper part of your uterus for your babies' growing legs and buttocks.
Most of the downy coat of hair (lanugo) that covered your twins from 26 weeks has disappeared. Most of the greasy whitish substance that covers their skin (vernix caseosa) has also been shed. Your twins will swallow their lanugo and vernix caseosa, along with other secretions, and store them in their bowels. They will become your baby's first poo, which is a blackish substance (meconium).
Your babies' amniotic fluid, once clear, is now pale and milky. The outer layers of their skin are also sloughing off as new skin forms underneath.
Light, usually painless contractions (Braxton Hicks) may start during the last two months of a singleton pregnancy, but can start much earlier if you are expecting twins. The pressure of a double pregnancy opens the neck of the uterus (cervix) much earlier, preparing you for labour and birth.
Find out what to expect from the early weeks with your babies.
Note: every baby develops differently. This page is designed to give a general idea of how babies grow in the uterus.
See your previous stage: 32 weeks pregnant
Last reviewed: May 2012