Pregnancies exposed to tramadol not at heightened risk of miscarriage, congenital malformations

Tramadol exposure during early pregnancy does not appear to contribute to an increased risk of spontaneous abortion or congenital malformations, a study reports.

Researchers used data from the Danish National Prescription Register. They matched pregnancies with maternal exposure to tramadol to pregnancies without maternal exposure to the drug using propensity scoring.

Out of 36,467 and 18,907 pregnancies included in the analyses of spontaneous abortion and major congenital malformations, 7,310 and 3,796 were exposed to tramadol, respectively.

Spontaneous abortion occurred in 893 (12.2 percent) pregnancies with maternal exposure to tramadol and in 3,471 (11.9 percent) pregnancies without such an exposure. Multivariable Cox proportional hazards regression showed that tramadol exposure conferred no risk increase in terms of miscarriage (hazard ratio, 1.06, 95 percent confidence interval [CI] 0.99–1.14).

Meanwhile, a major congenital malformation occurred in the offspring of 151 (4.0 percent) pregnancies with maternal exposure to tramadol and in 579 (3.8 percent) in pregnancies without such an exposure. Multivariable log binominal models revealed no association between tramadol exposure in pregnancy and risk of major congenital malformations (relative risk, 1.04, 95 percent CI, 0.87–1.24).

Opioids, such as tramadol, can cross placental and blood-brain barriers, thereby posing risks for foetuses and newborns who are exposed to such drugs in utero. Prenatal opioid exposure has been implicated in spontaneous abortion, premature rupture of membranes, pre-eclampsia, abruption placentae, and foetal death. Adverse neonatal outcomes have also been associated with opioid use during pregnancy, including preterm birth, small for gestational age, lower birth weight, reduced head circumference, and sudden infant death. [Pediatrics 2017;139:e20164131]