Single dose v two-dose antenatal anti-D prophylaxis: a randomised controlled trial

Area of Science:

• Obstetrics and Gynecology
• Immunology
• Maternal-Fetal Medicine

Background:

• Rh(D) alloimmunization is a significant risk in Rh(D)-negative women carrying Rh(D)-positive fetuses.
• Antenatal anti-D prophylaxis (RAADP) is crucial for preventing Rh(D) sensitization.
• Optimizing RAADP regimens is essential for maximizing protection.

Purpose of the Study:

• To compare the detectability of circulating Rh(D)-immunoglobulin (anti-D) at delivery between single and two-dose antenatal anti-D prophylaxis (RAADP) regimens.
• To assess and compare compliance rates with the single and two-dose RAADP regimens.

Main Methods:

• An open-label, randomized controlled trial was conducted involving 277 Rh(D)-negative pregnant women.
• Participants received either a single 1500 IU dose of anti-D at 28 weeks or two 625 IU doses at 28 and 34 weeks.
• Primary outcome: detectable anti-D levels at delivery; Secondary outcome: compliance with the RAADP regimen.

Main Results:

• Detectable circulating anti-D levels at delivery were significantly higher in the two-dose group (86%) compared to the single-dose group (56%; P < 0.001).
• Compliance rates did not significantly differ between the single-dose (61%) and two-dose (50%) groups (P = 0.06).

Conclusions:

• The two-dose RAADP schedule provides superior protection against Rh(D) sensitization compared to a single-dose regimen.
• Current Australian recommendations for a two-dose RAADP schedule are supported by these findings.