What of the mother's tummy?
Examination of the abdomen in the first and second trimester is pretty accurate in determining the gestational age as long as the examiner knows what he or she is looking for. This also depends on things being normal with a singleton pregnancy. It is pretty useless in this respect for multiple pregnancy. Of course, examination of the abdomen is still valid for all the other purposes, even in multiple pregnancy.
For most of the first trimester, the womb is inside the pelvic cavity and abdominal examination will be negative. This is until near the end of the first trimester. In fact, the fundus (top) of the uterus just emerges at the bikini-line level at twelve weeks.
It is not uncommon to see a celebrity photographed showing an apparent "three-months bump". There is nothing like a three-month bump, unless the lucky mother-to-be is carrying triplets.
The fetus continues to increase in size and the various organs are maturing functionally. The amount of water (amniotic fluid) is also increasing. It follows that the fundus of the uterus will continue rising and therefore the belly grows bigger. The womb's ability to increase in size and accommodate the weight of its contents is quite amazing. At conception, the uterus is about the size of a small fist, weighing about 50 g. By the end of the third trimester, it will extend from inside the pelvis to the diaphragm beneath the ribs, weighing about 1000 g - twenty times its original weight, and that is minus its contents!
In a few weeks after delivery, the uterus will shrink back to its original size, or very close to it.
Braxton-Hicks contractions are common and could start as early as the middle of the second trimester. A person examining the abdomen may feel these, but the mother is mostly unaware of them. She may start feeling them in the third trimester. They are usually irregular, unpredictable, short-lived and painless. The frequency may increase towards the end of pregnancy, to the extent of causing anxiety of impending labour. If one is unlucky, this stage may last three or four weeks, a grim prospect. Fortunately, this is unusual.
This is where a lot of people tie themselves in a twist. What does a phrase like "a baby born two weeks premature" mean? In fact, it doesn't mean anything!
"Term" is a period stretching a good five weeks. Once a pregnancy reaches thirty-seven completed weeks, it is already term. A week or four weeks later, if the baby hasn't arrived yet, it will still be "term" and still normal. Any baby born in the period stretching from thirty-seven to forty-two weeks will therefore be born at "term". It also means, a parent who makes a reference to a child that was born "five days late", implying that he or she arrived five days after the calculated due date (EDD) is right, in a figure of speech. However, it is a technically misleading term, because it may create the impression that the baby arrived after "term", which is incorrect.
It is therefore appropriate to refer to the actual duration of pregnancy (thirty-four weeks, thirty-eight weeks, forty-one weeks, etc.) rather than to extrapolate figures from the expected date of delivery.
Term is characterized by differing degrees of discomfort, but discomfort there will be.