To start off, pre-pregnancy the uterus is the size of an orange or the size of the folded fist and is situated deep in the pelvis just behind your bladder. Uterus grows during pregnancy to accommodate the growing baby.
Uterus Size During Pregnancy: First Trimester
Around 12 weeks pregnant, the uterus grows a little bigger to the size of a bigger orange or a grapefruit, but it still fits in the pelvis. The growing size of the uterus can make increase the frequency of urination.
Uterus Size During Pregnancy: Second Trimester
During the second trimester, your uterus will grow to the size of a papaya. Uterus no longer fits inside the pelvis. It will be situated midway between the navel and breasts.
As the uterus grows, it starts pushing organs out of their usual places and puts tension on surrounding muscles and ligaments. This may cause some aches and pains which are typical of pregnancy, they are completely normal. Starting between 18 and 20 weeks your doctor will start measuring the distance from your pubic bone to the top of your uterus in centimetres at every visit. The top of your uterus is called the fundus, so the measurement is called the fundal height. This helps in estimating the number of weeks of pregnancy and also the growth of the baby. It is an approximate and usually is one or two weeks off. For example, if you measure 30 centimetres then you should be about 30 weeks pregnant give or take a week or two. If the measurements are very different from your gestational age then the doctor may do some additional tests to make sure everything is normal.
Uterus Size During Pregnancy: Third Trimester
This is the last trimester and the uterus grows maximum during this trimester. It can grow up to the size of a watermelon. When you reach full term your uterus will extend from the pubic area to the bottom of your rib cage. During the last few weeks of pregnancy, the uterus usually drops lower into the pelvis.
Uterus Size After Pregnancy
After birth, the uterus will gradually return to its pre-pregnancy size and position in about 6 to 8 weeks. The return of uterus to its pre-pregnancy size is called involution of the uterus.