Pregnancy Myths

Is hair color safe? Will having sex harm your baby? Is there a correlation between a large appetite and having a boy? Here’s what science can back up.

Along with well-meaning advice from all the pregnancy experts in your life — including strangers on the street who touch your belly — you’ve most likely heard the “facts”, stories and predictions about pregnancy for years.  Stated with authority, no doubt. When they sometimes actually turn out to be true, is it just coincidence — or are they backed by science?

Here is the lowdown on what you may have heard.

You Should Be Eating for Two
Although the growing fetus is a unique and separate person, she is only a few pounds. Most weight gain occurs in the second half of pregnancy, and the recommended gain for a woman of normal weight is 25 to 35 pounds. This equates to just 300 extra calories per day, the amount found in half of a PB&J sandwich and a glass of milk. Remember that eating for two people is sure to make the postpartum weight loss a real challenge!


Don’t Color You Hair
Hair coloring is safe, if done properly. Chemicals used to color hair are absorbed in small amounts only, are thought to be safe. More worrisome are the harsh fumes, especially arising from ammonia-based products, so hair coloring should be done in a well-ventilated space to avoid nausea and other symptoms.

Having Sex Will Hurt Your Baby
Intercourse will not hurt your baby. The thick and firm cervix functions to protect the growing pregnancy. In certain situations — including placenta previa, preterm labor and cervical insufficiency — intercourse should be avoided, with your healthcare provider will discuss with you. But in a normal, healthy pregnancy, intercourse is not discouraged and may function as a stress reliever and as a way to maintain intimacy during the long nine months. It may also help get you into labor as you approach your due date!

Spicy Foods Will Cause Colic
Colic — long periods of unexplained crying that are recurrent — is very difficult for parents. However, there is no evidence to show that maternal consumption of spicy or exotic foods will contribute to colic in newborns. Although the mother may experience heartburn or gastrointestinal upset, the baby’s digestive system is completely separate.

Heartburn Leads to Lots of Hair
Heartburn is exceedingly common in pregnancy, tends to be worse in the third trimester, and is related to the effects of estrogen causing the lower esophageal sphincter to relax and gastric contents to reflux. For ages, it has been speculated that severe reflex tends to correlate with a full head of hair on your newborn. Although the science behind it is not understood, a recent study published out of Johns Hopkins may suggest some truth to the myth of association (but not necessarily causation). While the jury is still out, the prevalence of heartburn is indisputable, and pregnant women should not hesitate to discuss symptoms with their healthcare provider, as there are many medications that can relieve symptoms.


Eating Peanut Butter During Pregnancy Will Lead to a Peanut Allergy In Your Child
Not true. Food allergies tend to run in families, along with other allergic conditions such as asthma and eczema. There is no reason to think that peanut butter consumption will cause an allergy in your child, and reasonable amounts of peanut butter may contribute to a healthy, high-protein diet.

A large Appetite Mean You Are Having a Boy
There may be some evidence to support the truth of this. Some studies, including one from Harvard, have shown that women who eat more carbohydrates, protein and fat are more likely to be carrying boys. These differences may be attributed to higher levels of circulating testosterone.

Sleeping on Your Back Is Dangerous
Sleeping on your back is not advised during the third trimester. This is because compression of the vena cava, a large vein that returns blood to the heart, can occur under a large uterus. However, it is unlikely that your baby would experience any ill effects from back sleeping, rather, you are likely to feel lightheaded and/or dizzy and change positions long before any damage is done. In earlier trimesters, pregnant women are encouraged to sleep in any position that they find to be comfortable.

Cocoa Butter Can Prevent Stretch Marks
Stretch marks are very common in pregnancy and tend to be determined genetically. While cocoa butter will moisturize your skin, making it soft to touch, it is unlikely to prevent the development of stretch marks. In addition, cocoa butter is from the cocoa plant and may contain measurable amounts of caffeine. If cocoa butter is used in excess, your body will absorb this caffeine, which could lead to a fast heart rate for mother and baby. So, it is advised to use cocoa butter in moderation in pregnancy.

Margaret K. Chory, MD, is a general obstetrician/gynecologist practicing in Pittsburgh, PA.

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Written by Margaret K. Chory, MD

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