Pregnancy Week By Week

Indeed, estrogen levels in the blood of expectant mothers can be up to one hundred times higher than normal.  Other causes of morning sickness may include:

• Low blood sugar (hypoglycemia) because the placenta drains energy from the mother,
• An increase in the hormone progesterone, which relaxes the muscles in the uterus and prevents early childbirth, but may also relax the stomach and intestines, leading to excess stomach acids and gastroesophageal reflux disease.
• An increase in human chorionic gonadotropin, and
• An increase in sensitivity to odors, which over-stimulates normal nausea triggers.

More than half of all pregnant women experience morning sickness, and despite the discomfort it can cause, many health care providers view it as sign that the placenta is developing well and the baby will be healthy. 

Morning sickness may not feel healthy, but it has evolutionary advantages.   For example, it can protect the fetus against poisonous foods that the mother might eat accidentally. Many plants contain chemical toxins that when eaten or smelled, could make a pregnant mother feel especially sick.  The livers and other organs of adult humans, like those of other animals, manufacture enzymes that destroy plant toxins, but a fetus is not so lucky; its defenses are not yet fully developed, and even small doses of plant toxins that have negligible effects on the adult can kill or hurt an embryo. 

Pregnancy sickness causes women to experience nausea when exposed to the smell or taste of foods that are likely to contain toxins injurious to the fetus, even though they may not be poisonous for her.  Some evidence for this argument includes the following: 

• Morning sickness is common among pregnant women, which suggests that it is an evolutionary adaptation; 
• Fetuses are most easily poisoned when they reach 3 months; this is also the time of peak susceptibility to morning sickness.
• Foods with the most toxins tend also to be those whose taste and odor cause the most disgust in women with morning sickness; and finally; 
• Women without morning sickness are more likely than mothers who do feel nausea to miscarry or to bear children with birth defects.

In addition to protecting the fetus, morning sickness may also protect the mother. Pregnant women have weakened immune systems, probably to reduce the chances of rejecting tissues of their own offspring.   Because of this, animal products containing parasites and harmful bacteria can be especially dangerous to pregnant women. There is evidence that animal products, both meat and fish, often trigger morning sickness.

Since morning sickness is a defense mechanism against the ingestion of toxins, doctors who prescribe anti-nausea medication to pregnant women may unwittingly increase the chances of birth defects or miscarriages because the mothers might then eat foods that are harmful to the baby.  On the other hand, agronomists have grown many domestic vegetables purposely to lower the levels of toxins that existed in their ancestral plants, so the embryo is probably not as vulnerable today as it was when the defense mechanism first evolved.

Every woman and every pregnancy are unique, so it is impossible to predict with 100% certainty when morning sickness will come and go.    However, in general morning sickness is very common in the first trimester of pregnancy and tends to disappear by the 13th week --or fourth month. Morning sickness is rarely more than an annoyance for the mother. 

Doctors can treat the mild cases with dietary measures, rest and antacids.  Severe cases do occur, however, and they often require a stay in the hospital so the mother can receive fluid and nutrition intravenously. In these extreme cases, known as hyperemesis gravidarum, the mother's body rejects any foods or fluids as a result of the nausea, and she loses more than two pounds. 

Vomiting may be severe enough to cause dehydration, weight loss, alkalosis and hypokalemia.  Hyperemesis gravidarum occurs in about 1% of all pregnancies, and it can cause severe health problems for both the baby and the mother, such as malnutrition and electrolyte imbalances.  Therefore, the condition requires treatment by a practitioner; the mother should avoid taking medications if a doctor has not specifically recommended them. 

The expecting mother should also see a doctor if she vomits black or bright red blood, or throws up more than four times in a day, or vomits up all the fluids she drinks for a day or more.
Some of the following strategies can help a pregnant mother tolerate morning sickness: 

• Small meals throughout the day that stave off feelings of hunger and fullness;
• Avoidance of foods that are rich, spicy, greasy or fatty, or have smells that make the mother nauseous;
• Drinking fluids 1/2 hour before or after a meal, but not with meals
• Drinking small amounts of fluids during the day to avoid dehydration
• A diet of bland foods and carbohydrates -- saltine crackers, gelatin desserts such as Jell-O, popsicles, chicken broths, ginger ale and pretzels, plain baked potato, white rice or dry toast;
• For some women, the avoidance of prenatal vitamins with iron. Morning sickness may be a side effect of taking iron.   
• "Acupressure" wristbands, used by some boat passengers to prevent seasickness, can be useful to hold morning sickness at bay.  They are available at some pharmacies.
• Asking someone else to cook meals; opening windows and turning on fans if odors are bothersome; 
• Getting plenty of rest and napping during the day;
• Avoiding warm places, because heat contributes to nausea;
• Sniffing lemons or ginger, drinking lemonade, or eating watermelon;
• Eating salty potato chips, which settle stomachs enough to tolerate a meal
• Exercising
• Avoiding naps or lying down immediately after eating
• Eating regularly

Expecting mothers should consult practitioners immediately:

1. In cases of excessive nausea and vomiting that prevents the from keeping any food down, 
2. If vomiting is accompanied by pain or fever
3. If nausea and vomiting persists well into the second trimester (after 13th week)

*This article is based on the information at http://familydoctor.org, http://www.americanpregnancy.org, http://en.wikipedia.org and http://www.nlm.nih.gov