Study suggests nifedipine helps prevent premature birth in-flight

In a study published in the Air Medical Journal (AMJ), researchers say their findings indicate that nifedipine used as a tocolytic can facilitate the successful aeromedical transfer of pregnant women at risk of pre-term birth, particularly when the drug is given early with prompt referral and if air medical retrieval is undertaken in a timely manner.

Jodie Martin and Jodie Mills, both midwives and flight nurses with CareFlight, Northern Territory, Australia, and David Stanley, professor in nursing at the University of New England and Charles Sturt University, Australia, note that previous studies have reported that air medical transfer of women in preterm labour can be safely accomplished without preterm birth occurring, and in many cases women were later discharged without preterm birth occurring. CareFlight, the air medical retrieval service that operates in the remote Top End region of the Northern Territory, has previously reported in-flight births despite the administration of nifedipine as a tocolytic, the study notes; but this new study was conducted to determine if the drug could help to improve birth outcomes in such transfers.

The researchers conducted a retrospective descriptive study over a three-year period of over 300 women transported in preterm labour (defined as ‘23 + 6 to 36 + 6 weeks’ gestation). The average gestation period was 32 + 2 weeks, the mean retrieval time was six hours, and the mean time of birth from referral was 33 hours. Seventeen per cent of the women included in the study gave birth to a preterm newborn in a remote health centre, and almost half of the women were discharged without a preterm birth occurring. However, there were three in-flight preterm births.

All women transported by air were admitted to the tertiary hospital for at least 24 hours. The majority (72 per cent) of women included in this new research were given tocolysis in the form of oral nifedipine; no other tocolytics were given. The three women who gave birth preterm in-flight had all received nifedipine upon referral.

The researchers state: “There is always the risk of preterm birth in-flight and/or before arrival at a tertiary hospital, particularly when involving a high-risk obstetric population from remote geographic regions. This study has been able to verify and add to the widely published literature that the majority of women transferred from rural areas are in fact discharged without preterm birth occurring.” They also conclude that nifedipine was used successfully to facilitate in utero transfers in many cases. The findings compare favourably with other published studies, they say.

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