What’s happening to the mother in week 13 and 14?
At weeks 13 and 14, the uterus is the size of a grapefruit. It is common for you to gain weight during this period. Weight gain is usually one to four kilograms. Gestational nausea has usually subsided and many people find that they are less tired and have more energy.
Development of the foetus
By now, the foetus is usually between 6 and 7 cm long and weighs around 40 grams, but this can vary from pregnancy to pregnancy. In early pregnancy, amniotic fluid is mainly produced from the mother's blood. Urine production starts as the foetus develops. The amniotic fluid then becomes a mixture of fluids from both the mother and the foetus. The amount of amniotic fluid gradually increases, providing the foetus with more space to move around freely.
During this period, the nails on the fingers and toes develop and the bones begin to harden.
By the time of transition to the second trimester, the placenta is fully developed. From now on, the placenta will transfer nutrients and oxygen to the foetus.