Although many people tell children, "There's a baby in my stomach," when they're pregnant, they know the baby is actually growing in the uterus, the female reproductive organ. There are pregnancy symptoms related to both the uterus and the stomach, including the gastrointestinal tract, and sometimes the same symptoms relate to both.
While the stomach doesn't actually grow during pregnancy like the uterus does, women do eat more during pregnancy, which can stretch out the stomach. Bloating in early pregnancy, which can distend the abdomen, can be caused by the slowdown of the intestines as a side effect of progesterone, a hormone produced in the uterus. Uterine growth can't be seen for the first 3 months of pregnancy, but around 12 weeks, the top of the uterus can just barely be felt right over the public bone. Uterine growth becomes very obvious in most women by the start of the third trimester, although many women complain they look "fat" rather than pregnant until after the 20th week, when the uterus rises above the level of the navel. Some women, mostly those who are overweight, never realize they're pregnant. Abdominal distention from gas and bloating and the growing uterus feel different; the uterus is firmer. By the end of 9 months, the uterus has grown enough to crowd the stomach and the intestines, often causing heartburn and gas and making it difficult to eat a lot at one time.
Nausea and Vomiting
Nausea and vomiting are common early pregnancy stomach-related symptoms that seem to have nothing to do with the uterus, but actually do. Nausea is most likely caused by an increase in human chorionic gonadotropin, a hormone produced by the placenta in the uterus; women carrying multiples often have more severe nausea. Progesterone may contribute to nausea by slowing down emptying time of the stomach and intestines. Three out of four pregnant women have either nausea or vomiting; half of all pregnant women suffer from both, usually starting around week 6 of pregnancy and continuing through week 14, BabyCenter says. Morning sickness is a misnomer; as any pregnant woman can tell you, morning sickness often continues all day long. Severe nausea and vomiting may increase the chance of preterm labor, BabyCenter states.
Uterine cramping and stomach cramping are both common during pregnancy. The uterus cramps as it grows, and toward the end of pregnancy develops practice labor contractions known as "Braxton-Hicks" contractions. Round ligament pain is common starting in the second trimester; the round ligaments support the uterus, and as they stretch to accommodate the growing weight, aching, cramping or sharp but temporary pain may occur on the sides of the abdomen, according to the American Pregnancy Association. Severe uterine cramping is not normal and should always be investigated. Stomach cramping in pregnancy can be related to nausea or because the crowding of the intestines late in pregnancy causes bloating, gas and constipation, the March of Dimes explains.