Risk of Water Diet Pills During Pregnancy

Along with weight gain during pregnancy, swelling of your hands and feet -- enough to make getting your rings off and wearing certain shoes difficult -- commonly occurs. You might consider taking prescription diuretics or buying "natural" herbal diuretics in the health food store, but don't, at least not unless your physician tells you to. Diuretics won't help reduce the normal swelling or weight gain associated with pregnancy and may have harmful effects. Do not take over-the-counter or prescription diuretics in pregnancy without your doctor's approval.

Every pregnant woman has an increase in blood volume during pregnancy of between 40 and 60 percent, Joy Jones, R.N., reports on Perinatal Support Services. You need the extra fluid volume to supply the baby and placenta with blood that contains nutrients, including oxygen. Water pills, medically known as diuretics, work by increasing the amount of sodium excreted by the kidneys. Sodium pulls more fluid out of the blood vessels and decreases the amount of circulating fluid.

When your blood volume decreases, you have less blood to circulate through to the fetus in pregnancy, which could deprive the fetus of necessary nutrients. When blood volume falls, the kidneys excrete extra renin, a substance that constricts the small blood vessels. This occurs in preeclampsia, one of the hypertensive issues of pregnancy. As the blood vessels constrict, blood pressure rises, which occurs in preeclampsia and could also occur with diuretic use, especially if you already have a tendency towards preeclampsia. This could trigger the start of preeclampsia in susceptible women, Joy Jones warns.

Problems associated with diuretic use in normal pregnancy include an increased risk of nausea and vomiting, according to a report in the January 2009 issue of the "Canadian Family Physician" that examined a number of studies. No evidence of increased risk of birth defects or electrolyte imbalances occurred in women taking diuretics for chronic high blood pressure present before pregnancy. Neonates had no increased risk of low platelet count or jaundice.

Diuretic use may increase fetal weight slightly, by an average of 3.6 oz. However, 10.3 percent of the women using diuretics in a Danish study published in the February 2001 "British Journal of Clinical Pharmacology" that showed a fetal weight increase when women took diuretics had diabetes, which increases fetal weight. Around 15 percent of the women had high blood pressure, which more than doubled the risk of having an infant with a birth weight less than 5.5 lbs.

Diuretic use may lead to preeclampsia by raising blood pressure in susceptible women. Complications of preeclampsia include intrauterine growth retardation, with low birthweight, premature delivery, placental abruption, maternal seizures, fetal or maternal brain damage or fetal or maternal death, in severe cases.