Lorazepam and Birth Defects
Based on FDA labeling and available evidence, lorazepam use during the first trimester of pregnancy should be avoided due to an increased risk of congenital malformations associated with benzodiazepines as a class, though specific defects linked to lorazepam remain uncertain. 1
FDA-Labeled Risks
The FDA drug label for lorazepam explicitly states that an increased risk of congenital malformations has been associated with the use of minor tranquilizers (including benzodiazepines like lorazepam) during the first trimester of pregnancy 1. The label emphasizes that "because the use of these drugs is rarely a matter of urgency, the use of lorazepam during this period should be avoided" 1.
Animal Study Findings
In reproductive studies, rabbits exposed to lorazepam showed occasional anomalies including:
- Reduction of tarsals, tibia, and metatarsals
- Malrotated limbs
- Gastroschisis
- Malformed skull
- Microphthalmia
However, these occurred without clear dose-relationship and have been reported randomly in historical controls 1.
Human Evidence for Specific Defects
Pulmonary Valve Stenosis
One case-control study found an association between lorazepam exposure and pulmonary valve stenosis (crude OR: 4.1; 95% CI: 1.2-14.2), though sample sizes were limited and confidence intervals wide 2.
Anal Atresia
A French registry study (1976-1997) identified a potential association between lorazepam and anal atresia (OR=6.2; 95% CI: 2.4-15.7). Among 6 cases of anal atresia in newborns exposed to benzodiazepines, 5 were specifically exposed to lorazepam 3. This finding requires replication in other datasets and should be considered preliminary.
Other Malformations
The 2019 National Birth Defects Prevention Study found elevated odds ratios for:
- Anophthalmia or microphthalmia with alprazolam (not lorazepam specifically)
- Dandy-Walker malformation with any benzodiazepine exposure
However, benzodiazepine use overall was rare (0.8% of pregnancies), and associations were imprecise 2.
Neonatal Effects Beyond Structural Defects
Infants born to mothers taking benzodiazepines late in pregnancy or at delivery may experience:
- Hypoactivity and hypotonia
- Hypothermia
- Respiratory depression and apnea
- Feeding problems
- Impaired metabolic response to cold stress
- Withdrawal symptoms during the postnatal period 1
Lorazepam crosses the placenta, with measurable levels in umbilical cord blood 1.
Clinical Context
One guideline mentions lorazepam can be used as part of prechemotherapy antiemetic regimens during the second and third trimesters of pregnancy for breast cancer patients, suggesting some clinical acceptance outside the first trimester 4. However, this represents a specific risk-benefit calculation in oncology settings where maternal mortality concerns may outweigh teratogenic risks.
Key Caveats
- Confounding by indication: Women taking benzodiazepines often have underlying anxiety or psychiatric conditions that themselves may influence pregnancy outcomes
- Limited sample sizes: Most studies of lorazepam specifically have small numbers of exposed pregnancies, resulting in imprecise risk estimates
- Class effect uncertainty: Whether risks are specific to lorazepam or represent a benzodiazepine class effect remains unclear
- Dose-response data lacking: Unlike some other medications, clear dose-dependent relationships have not been established for lorazepam
Practical Recommendations
If a woman of childbearing potential requires lorazepam, she should be counseled about pregnancy risks before initiating therapy. If pregnancy occurs during treatment, the patient should immediately contact her physician to discuss discontinuation, recognizing that abrupt cessation in physically dependent patients carries its own risks 1.