Morning sickness affects 50 percent to 90 percent of all pregnant women. However, if you haven't noticed any unusual nausea during your pregnancy, this isn't necessarily a cause for concern. There are many reasons a woman might not experience morning sickness, and many women who avoid it completely have completely healthy infants.
Morning Sickness
Morning sickness typically begins around the sixth week of pregnancy. It can occur at any time of the day. The precise cause of morning sickness is unknown, but hormone fluctuations, an enhanced sense of smell during pregnancy or a sensitive gastrointestinal tract may be to blame. There may be a genetic component, because women with a mother or sister who experienced morning sickness are more likely to develop it. Most pregnant women experience relief from morning sickness by the 14th week of pregnancy.
Lack of Pregnancy Nausea
Although women who have miscarriages frequently report a lack of morning sickness, the absence of nausea occurs in many women with perfectly healthy babies. Many things besides the health of your baby can keep your body from reacting to your pregnancy with an upset stomach. For example, women carrying boys generally experience less nausea than mothers of girls. Also, mothers-to-be with lower levels of a particular naturally occurring bacteria in their stomachs may also escape pregnancy nausea.
Response
If you haven't experienced any nausea by the sixth or seventh week of pregnancy, it probably isn't a concern -- especially if your mother or sisters had pregnancies without morning sickness or if you're not prone to motion sickness when not pregnant. If you are concerned, a doctor can perform further tests to check on the health of your baby. A fetal Doppler or ultrasound can ensure that your pregnancy is progressing normally and your baby is healthy. Besides, an absence of nausea at six or seven weeks pregnant doesn't necessarily mean you won't develop it later.
Considerations
According to a September 2000 article in "Discover magazine," morning sickness may be an evolutionary adaptation that helps pregnant women stay away from foods that might be dangerous to the developing fetus. Even if you're missing this bodily signal to watch what you eat, you can still pay attention to what you consume during pregnancy. Avoid eating undercooked meat or eggs, deli meat, soft-serve ice cream, unpasteurized or soft cheeses and cooked foods that have been left at room temperature for more than an hour.
