Methamphetamines and pregnancy outcomes

Methamphetamine (MA) is one of the most commonly used illicit drugs in pregnancy, yet studies on MA-exposed pregnancy outcomes have been limited because of retrospective measures of drug use; lack of control for confounding factors; other drug use, including tobacco; poverty; poor diet; and lack of prenatal care. This study presents prospective collected data on MA use and birth outcomes, controlling for most confounders.

This is a retrospective cohort study of women obtaining prenatal care from a clinic treating women with substance use disorders, on whom there are prospectively obtained data on MA and other drug use, including tobacco. Methamphetamine-exposed pregnancies were compared with non-MA exposed pregnancies and non-drug-exposed pregnancies, using univariate and multivariate analysis to control for confounders.

One hundred forty-four infants were exposed to MA during pregnancy, 50 had first trimester exposure only, 45 had continuous use until the second trimester, 29 had continuous use until the third trimester, but were negative at delivery, and 20 had positive toxicology at delivery. There were 107 non-MA-exposed infants and 59 infants with no drug exposure. Mean birth weights were the same for MA-exposed and nonexposed infants (3159 g vs 3168 g; P = 0.9), although smaller than those without any drug exposure (3159 vs 3321; P = 0.04), infants with positive toxicology at birth (meconium or urine) were smaller than infants with first trimester exposure only (2932 g vs 3300 g; P = 0.01). Gestation was significantly shorter among the MA-exposed infants than that among nonexposed infants (38.5 vs 39.1 weeks; P = 0.045), and those with no drug exposure (38.5 vs 39.5; P = 0.0011), the infants with positive toxicology at birth had a clinically relevant shortening of gestation (37.3 weeks vs 39.1; P = 0.0002).

Methamphetamine use during pregnancy is associated with shorter gestational ages and lower birth weight, especially if used continuously during pregnancy. Stopping MA use at any time during pregnancy improves birth outcomes, thus resources should be directed toward providing treatment and prenatal care.