If you're like the majority of pregnant women, you'll experience morning sickness to one degree or another. Morning sickness generally arises around the sixth week of pregnancy, and lasts until the end of the first trimester, though some women experience longer or shorter periods of symptoms. The hormone hCG is responsible for much of the sensation of morning sickness.
Role of HCG
HCG, short for human chorionic gonadotropin, is a hormone that your developing embryo produces. The purpose of the hormone is to communicate to your body that you're pregnant, which helps to maintain the lining of the uterus and gives the embryo a place to implant. Typically, hCG levels start rising around a week after conception, and continue rising through the third or fourth month of pregnancy, at which point they start to level off and drop.
Morning Sickness
As your hormone levels rise early in pregnancy, it's quite common to feel very nauseated, explain Heidi Murkoff and Sharon Mazel in their book "What To Expect When You're Expecting." The nausea typically strikes when your blood sugar is low, which is why it's so common to feel queasy in the morning. Murkoff and Mazel note that morning sickness can strike any time of day, however.
Time Frame
HCG levels in the blood explain the time frame during which most women experience morning sickness, explains Dr. Miriam Stoppard in her book "Conception, Pregnancy and Birth." Most women have measurable quantities of hCG in their blood by a week or two after conception--this is the third or fourth week of pregnancy--but levels typically are not high enough to cause symptoms until two or more weeks later, because hCG doubles every 48 to 72 hours. By the start of the third trimester, you're typically getting accustomed to the higher hormone levels and feel less nauseated.
Detecting Pregnancy
Because morning sickness is caused by hCG, the very same hormone that home pregnancy tests check for, you can use morning sickness as an early indicator of pregnancy. Typically, by the time you're feeling nauseated in the morning, there's plenty of hCG in your bloodstream, and therefore enough hCG in your urine for a home pregnancy test to note the presence of the hormone. If you might be pregnant and you're feeling morning sickness-like nausea but a home pregnancy test turns up negative, repeat the test in a week, explains Dr. Stoppard.
Prevention/Solution
There's little that you can do to prevent morning sickness entirely, note Murkoff and Mazel. Regardless, there are a few things you can do to try to diminish the impact of the symptoms, until you grow accustomed to the higher levels of hCG in your blood. Ginger--in foods, in tea or in the form of candy--can help relieve symptoms, and some women find lemon helpful as well. Murkoff and Mazel particularly recommend eating small snacks throughout the day to keep blood sugar high.
References
- "What to Expect When You're Expecting"; Heidi Murkoff and Sharon Mazel; 2008
- "Conception, Pregnancy and Birth"; Miriam Stoppard, M.D.; 2008
