November 1, 2006 In 2004, there were more than 4.1 million births in the U.S. The time from conception until birth is about 40 weeks, or nine months. During pregnancy, a womans body undergoes many changes. During the first trimester (the first three months), pregnant women may experience nausea, tiredness, back ache and mood swings. The growing uterus can press on the bladder and lead to a need for frequent urination. By the end of the third month, the average weight gain for the mom is about three to five pounds. The baby will be about three inches long and weigh about one-half of an ounce. During the second trimester, nausea and tiredness tend to subside. However, women are more likely to experience aches and pains (especially back ache), shortness of breath and skin changes. The mom gains weight much faster - about one to two pounds a week. At the end of the second trimester, the baby is about 13 inches long and weighs about 1¾ pounds. Fatigue and body discomforts may return during the third trimester. The growing fetus taxes the body and puts extra pressure on the abdominal organs. Heartburn, frequent urination, hemorrhoids and difficulty sleeping are common complaints at this stage. Mom continues to gain weight at a rate of about one to two pounds a week. By the end of the pregnancy, the baby is about 20 to 22 inches long and weighs about 7½ pounds. Myths Surrounding Pregnancy Pregnancy is a time of anticipation for many families. Parents may wonder, "Is it going to be a boy or a girl?" or "Will the baby be healthy?" There are many myths or old wives` tales surrounding pregnancy. One of the most common myths surrounds the sex of the baby. One tale states that a woman with a low, round belly (like a basketball), is likely to have a boy, while a wider or higher belly indicates a girl. In truth, how a woman carries her baby is related to abdominal and uterine muscle tone and the position of the baby. Another gender myth revolves around the womans complexion - a pregnant woman with acne is likely to have a boy, while a clear complexion means a girl. This myth is based on the idea that increased testosterone production in a male fetus can lead to acne breakouts in the mom. However, there is no scientific proof to support this claim. Ironically, another myth states that a poor complexion means the woman is carrying a girl, because a female fetus "steals" the mothers beauty. Truthfully, the only way to definitively know the sex of the unborn baby is through prenatal genetic testing. Another popular pregnancy myth revolves around heartburn and the amount of hair on a new babys head. Supposedly, if a woman experiences a lot of heartburn during her pregnancy, the baby will have a full head of hair at birth. There is no proof for this theory. In fact, research shows that heartburn is very common - affecting up to 50 percent of pregnant women. Some other myths are related to potential health concerns in the mom. Some women are afraid to exercise during pregnancy because they fear the stress will harm the baby. During exercise, blood flow is increased to the skeletal muscle, heart and skin to provide extra oxygen to these vital structures. There is some evidence that blood flow to the placenta is slightly decreased during exercise. However this does not appear to pose a problem in healthy women with low-risk pregnancies. In fact, research shows exercise helps to maintain fitness during pregnancy and may decrease risk of insomnia and anxiety. The American College of Obstetricians and Gynecologists (ACOG) recommends that a healthy woman with a low-risk pregnancy get at least 30 minutes of exercise a day over most days of the week. Diet is an important concern for pregnant women. Some women wont eat fish because of the concerns about potential exposure to mercury. A toxic form of mercury, called methylmercury, can be absorbed by fish, then ingested by humans who eat the contaminated fish. Prenatal exposure to methylmercury may be associated with increased risk for delay in walking and speech and problems with memory and attention. ACOG recommends that pregnant women avoid shark, swordfish, king mackerel and tilefish, which may contain large amounts of mercury. However, women can safely consume about 12 ounces of other types of cooked fish/week. Some women are concerned about the use of hair dye during pregnancy. One study suggests a slight increase in risk for neuroblastoma (a type of cancer) in babies born to women who used hair dye in the month before or during pregnancy. Another study found no association between hair dye use and development of childhood brain tumors. So there is no clear-cut evidence for either side. Dealing with Pregnancy Myths Obstetrician Jennifer Williams, M.D., says many pregnancy myths survive because women like to have fun trying to predict or guess the outcome of a pregnancy. In some cases, the beliefs are harmless guessing games (like predicting the sex of the baby or how much hair the baby will have). In other cases, that "friendly advice" may be detrimental to the health of the mom and/or baby (such as when a woman stops exercising or eats a very restricted diet). Women who are concerned about the safety of recommendations should talk to their health care provider. AUDIENCE INQUIRY If you have any specific questions or concerns about your pregnancy, talk with your health care provider. For general information on pregnancy: American College of Obstetricians and Gynecologists, http://www.acog.org American Pregnancy Association, http://www.americanpregnancy.org BIBLIOGRAPHY "About Pregnancy Weight Gain," Irving: American Pregnancy Association, downloaded from website (http://www.americanpregnancy.org), September 22, 2006. "Births: Final Data for 2004," National Vital Statistics Reports, September 29, 2006, Vol. 55, No. 1. Efird, J., et al., "Beauty Product-Related Exposures and Childhood Brain Tumors in Seven Countries," Journal of Neurooncology, April 2005, Vol. 72, No. 2, pp. 133-147. "Exercise During Pregnancy," Washington, DC: American College of Obstetricians and Gynecologists, downloaded from website (http://www.acog.org/publications/patient_education/bp119.cfm), October 15, 2006. Gliori, Gemma, et al., "Fish Consumption and Advisory Awareness Among Expectant Women," Wisconsin Medical Journal, 2006, Vol. 105, No. 2, pp. 41-44. Hindmarsh, Peter, et al., "Intrauterine Growth and its Relationship to Size and Shape at Birth," Pediatric Research, 2002, Vol. 52, pp. 263-268. McCall, E., et al., "Maternal Hair Dye Use and Risk of Neuroblastoma in Offspring," Cancer Causes and Control, August 2005, Vol. 16, No. 6, pp. 743-748. Morris, Stephanie, M.D., and Natasha Johnson, M.D., "Exercise During Pregnancy," The Journal of Reproductive Medicine, March 2005, Vol. 50, No. 3, pp. 181-188. Muallem, M., and N. Rubeiz, "Physiological and Biological Skin Changes in Pregnancy," Clinics in Dermatology, March-April 2006, Vol. 24, No. 2, pp. 80-83. "Nutrition During Pregnancy," Washington, DC: American College of Obstetricians and Gynecologists, downloaded from website (http://www.acog.org/publications/patient_education/bp001.cfm), October 16, 2006. Oken, Emily, et al., "Maternal Fish Consumption, Hair Mercury and Infant Cognition in a U.S. Cohort," Environmental Health Perspectives, October 2005, Vol. 113, No. 10, pp. 1376-1380. Park, Sohyun, Ph.D., and Mary Ann Johnson, Ph.D., "Awareness of Fish Advisories and Mercury Exposure in Women of Childbearing Age," Nutrition Reviews, May 2006, Vol. 64, No. 5, pp. 250-256. "Pregnancy Symptoms - Early Signs of Pregnancy," Irving: American Pregnancy Association, downloaded from website (http://www.americanpregnancy.org), September 22, 2006. Richter, Joel, M.D., "Gastroesophageal Reflux Disease During Pregnancy," Gastroenterology Clinics of North America, March 2003, Vol. 32, No. 1, pp. 235-261.