Background Beta-blockers have been used for many decades in pregnancy: to treat hypertension, supraventricular and ventricular tachycardias and as prophylaxis against aortic root dilatation. Evidence suggests that the use of beta-blockers is associated with intrauterine growth restriction (IUGR), oligohydramnios and premature labour. It has been proposed that this could be the result of underlying hypertension.

Aims To assess if beta-blocker medication is an independent risk factor for IUGR in non-hypertensive women with heart disease.

Design Retrospective case-control study.

Method A case note and data base review was undertaken at a tertiary referral centre from January 2002- August 2011. Women requiring beta blockade in pregnancy for non-hypertensive heart disease were compared to age and race matched controls. Women with left sided obstructive heart disease and impaired systemic ventricular function were excluded.

Primary Birth weight standardised for gestational age. Secondary: Perinatal morbidity, admission to SCBU, gestation of delivery, hypoglycaemia, mode of delivery.

Results 26 women taking beta-blockers were compared to 34 controls. Compared to controls, taking beta-blockers was associated with smaller birth weight (3015g v 3423g, p= 0.004, corrected for centile, p= 0.03). There was a trend towards increased IUGR < 10^th centile (19% vs 6% p= 0.119), increased SCBU admissions (15% vs 3% p= 0.156), and neonatal hypoglycaemia (19% vs 3% p = 0.075).

Conclusion Beta blockade in pregnancy results in low birth weight, and a trend to neonatal complications in non-hypertensive women. The drugs themselves cause significant fetal complications independent of maternal hypertension and should be avoided in pregnancy if possible.