From the FDA Drug Label
Use in Specific Populations 8. 1 Pregnancy Pregnancy Category C: There are no adequate and well-controlled studies in pregnant women. In nonclinical studies in mice, rats, and rabbits, gabapentin was developmentally toxic when administered to pregnant animals at doses similar to or lower than those used clinically. Gabapentin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus When pregnant mice received oral doses of gabapentin (500 mg, 1000 mg, or 3000 mg/kg/day) during the period of organogenesis, embryo-fetal toxicity (increased incidences of skeletal variations) was observed at the two highest doses The no-effect dose for embryo-fetal developmental toxicity in mice was 500 mg/kg/day or approximately ½ of the maximum recommended human dose (MRHD) of 3600 mg/kg on a body surface area (mg/m2) basis In studies in which rats received oral doses of gabapentin (500 to 2000 mg/kg/day), during pregnancy, adverse effect on offspring development (increased incidences of hydroureter and/or hydronephrosis) were observed at all doses. The lowest effect dose for developmental toxicity in rats is approximately equal to the MRHD on a mg/m2 basis When pregnant rabbits were treated with gabapentin during the period of organogenesis, an increase in embryo-fetal mortality was observed at all doses tested (60 mg, 300 mg, or 1500 mg/kg). The lowest effect dose for embryo-fetal developmental toxicity in rabbits is less than the MRHD on a mg/m2 basis
The use of gabapentin during pregnancy, especially at 22 weeks, is not recommended unless the potential benefit justifies the potential risk to the fetus. Key points to consider:
- Developmental toxicity was observed in nonclinical studies in mice, rats, and rabbits at doses similar to or lower than those used clinically.
- Embryo-fetal toxicity and mortality were increased in these studies.
- The no-effect dose for embryo-fetal developmental toxicity in mice was approximately ½ of the maximum recommended human dose.
- Adverse effects on offspring development were observed in rats at all doses tested.
- The lowest effect dose for developmental toxicity in rabbits is less than the MRHD on a mg/m2 basis. Given the potential risks, gabapentin should be used with caution during pregnancy, and the decision to use it should be made on a case-by-case basis, considering the potential benefits and risks 1.
From the Research
Gabapentin should be used with caution during pregnancy, including at 22 weeks gestation, and only when the potential benefits outweigh the risks. The most recent and highest quality study, published in 2024 2, suggests that gabapentin exposure during pregnancy is associated with an increased risk of preterm birth, preeclampsia, small-for-gestational-age, and NICU admission. This study, a systematic review of 27 high-quality studies, provides the most up-to-date and comprehensive evidence on the safety of gabapentin during pregnancy.
Key points to consider when using gabapentin during pregnancy include:
- The potential increased risk of adverse neonatal and maternal outcomes, such as preterm birth, small for gestational age infants, and neonatal complications 3
- The need for careful evaluation of the benefit-risk balance for both mother and fetus/infant when using gabapentin during pregnancy 2
- The importance of using the lowest effective dose and closely monitoring the patient if gabapentin is deemed necessary during pregnancy
- The consideration of alternative treatments with better established safety profiles during pregnancy, if appropriate
It is essential to note that the evidence on the safety of gabapentin during pregnancy is still limited, and more research is needed to fully understand its effects. However, based on the current evidence, gabapentin should be used with caution and only when the potential benefits outweigh the risks. If a pregnant woman is already taking gabapentin, she should not stop it abruptly without medical supervision, as sudden discontinuation could lead to withdrawal symptoms or worsening of the underlying condition being treated.