Final results from the Betaseron Pregnancy Registry



The Betaseron Pregnancy Registry was a voluntary, prospective, observational, exposure registration and follow-up study. Women with an existing pregnancy who had been exposed to interferon β-1b at any time after the first day of the last menstrual period (LMP), or during pregnancy but before any prenatal screening (eg, ultrasound and amniocentesis), were prospectively enrolled in the registry. Follow-up continued from enrolment through the 4-month paediatric visit.

The primary outcome measure was the rate of major congenital malformations in infants exposed to interferon β-1b during gestation, defined as any time after the first day of the mother’s LMP. Secondary outcome measures included the prevalence of spontaneous abortion and other negative pregnancy outcomes in exposed women.

The registry enrolled 99 pregnant women; three were lost to follow-up. The prevalence of elective abortion, stillbirth, ectopic pregnancy, neonatal death and maternal death was assessed. Pregnancy outcomes were classified as live birth, spontaneous abortion (SABs), elective abortion or fetal death/stillbirth. Infant assessments were made at birth for 86 babies, up to three months of age for 74 babies and at four months for 59 babies. There were 99 birth outcomes (three twins) including 86 (86.9%) live births, 11 (11.1%) SABs and 2 (2%) stillbirths. Birth defects were reported in five (5.1%) cases. Both stillbirths occurred in black women with a history of prior spontaneous abortion and other comorbidities that may have affected birth outcomes. The prevalence of spontaneous abortion in the Betaseron Pregnancy Registry (11.5% (95% CI 5.9 to 19.6)) was not significantly different from the 16% estimate for the general population of the USA. Rates of birth defects and SABs were not significantly different from population comparators. No developmental concerns were identified at the four-month paediatric visit.

There was no pattern to suggest an increased risk of birth defects in infants or an increased rate of spontaneous abortions in women after exposure to interferon β-1b during pregnancy. Infant assessments, such as birth weight, birth length and head circumference, also did not differ from population estimates and the 4-month infant follow-up did not identify any developmental concerns. Nevertheless, owing to low sample size, definitive conclusions cannot be drawn from the Betaseron Pregnancy Registry data.

Authors: Coyle PK, Sinclair SM
Source: BMJ Open. 2014 May 12;4(5):e004536. doi: 10.1136/bmjopen-2013-004536.
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