New research shows that babies born to methamphetamine-using moms face much higher risks of serious complications, compared to babies not exposed in the womb to this illegal street drug.

Life-threatening pregnancy complications, such as uncontrolled high blood pressure, are also more common among women who use methamphetamine while pregnant, the researchers found.

Methamphetamine, also called meth, is a highly addictive stimulant that users inject, snort, smoke or swallow. A form called crystal meth looks like fragments of glass and is smoked using a glass pipe like those used to smoke crack cocaine.

Methamphetamine use among U.S. women continues to be a serious problem. A recent study found that over the last 15 years, methamphetamine abuse has become the most common reason for pregnant women to seek drug counseling.

Dr. Ido Solt of Cedars-Sinai Medical Center in Los Angeles and colleagues decided to look into meth use in pregnant women after treating three pregnant patients admitted to the intensive care unit with uncontrolled high blood pressure. “The common denominator was methamphetamine use,” Solt told Reuters Health.

To better characterize the risks of meth use in pregnancy, he and his colleagues compared 276 meth-using women who delivered babies at a Phoenix hospital from 2000 through 2006 to 34,055 “control” women who delivered babies during the same time period at the same hospital. The meth users had either admitted to using meth while pregnant, or tested positive for the drug.

During the study period, the number of pregnant meth users the researchers identified steadily rose: from 22 in 2001, to 43 in 2004, to 77 in 2005.

On pretty much every measure Solt and his team looked at, the methamphetamine users and their babies fared worse.

Half of the meth users delivered their babies preterm, compared to 17 percent of the control population of women. Twenty-nine percent of meth users had C-sections, compared to 23 percent of control women.

Nearly 20 percent of pregnant meth users had uncontrolled high blood pressure, while nearly 10 percent suffered placental abruption, in which the placenta separates from the uterus before delivery. While the researchers didn’t have data on rates of these two complications for the non-meth-users in the study, both are rare; for example, recent research suggests that placental abruption occurs in less than 1 percent of births in the US.

Solt’s team also found that more than two-thirds of the women who had used meth reported fewer than five prenatal care visits, compared to 10 percent of the control women.

Six percent of the babies of meth users had low scores on a test designed to measure newborn health, compared to 1 percent of the control group babies. Four percent of the babies exposed to meth died soon after birth, compared to 1 percent of the control group babies.

Solt and his colleagues also found that nearly a quarter of the meth-using women reported being victims of domestic violence while pregnant. Forty percent of the meth-exposed babies were taken from their mothers at least temporarily, to be adopted, placed in Child Protective Services or foster care, or cared for by another person.

Meth users were older, and more likely to be white and English-speaking, than the control population. Only 12 percent were married, compared to 46 percent of control women.

These demographic characteristics might help doctors spot women at risk for using meth while pregnant, Solt noted. One might think that it would be easy to identify a pregnant meth user, but the researchers found otherwise. While the stereotypical meth addict has bad teeth, a gaunt body, and skin sores, many of the meth-using women didn’t fit this profile.

“We were surprised to encounter a significant proportion of the methamphetamine users that did not look like the typical user, and they were discovered through the toxicity screen,” the researcher said. Because urine tests can only identify the drug within three days of use, he added, screening might have missed some women who had used meth in their pregnancy.

While meth exposure is clearly dangerous to the developing baby, the researcher added, much remains unknown about how the drug hurts the fetus, or whether meth-exposed babies will experience lasting consequences.

“We have many black holes in our knowledge about the mechanism of harm,” he said.

SOURCE: Obstetrics & Gynecology, August 2010.