Association of maternal immunoglobulin G levels with pregnancy outcomes in primary immunodeficiency: A retrospective single-center study.

Pregnancy management in women with primary immunodeficiencies (PIDs) is an increasing clinical focus due to improved life expectancy. However, evidence guiding optimal maternal immunoglobulin G (IgG) levels to ensure favorable outcomes is limited, with no consensus on therapeutic targets. This study aimed to evaluate the association between maternal IgG levels, both preconceptionally and during the third trimester, and pregnancy outcomes in women with PIDs. We conducted a retrospective, single-center study reviewing medical records of 25 pregnancies in 18 women with a confirmed PID diagnosis. Key clinical and immunological parameters were analyzed. Associations between maternal serum IgG levels (measured preconceptionally and in the third trimester) and maternal, obstetric, and neonatal outcomes were assessed. A third-trimester IgG threshold of 1000 mg/dL was used for risk stratification analysis. The live birth rate was 80%. Pregnancies resulting in live birth were associated with significantly higher preconceptional IgG levels (median 1090.0 vs 421.0 mg/dL, P = .002) and a longer duration since PID diagnosis (median 62.0 vs 12.0 months, P = .007). The primary finding was that third-trimester IgG levels below 1000 mg/dL were strongly associated with an increased rate of maternal infections (55.6% vs 0.0%; odds ratio 27.5, 95% CI: 1.21-625.41; P = .008). No clear statistical association was found between IgG levels and most neonatal outcomes, including preterm birth or low birth weight. Third-trimester maternal IgG levels are a strong predictor of infection risk during pregnancy in women with PID. Additionally, higher preconceptional IgG levels are associated with successful live births, highlighting the importance of pre-pregnancy immune optimization. Although these findings from a small, retrospective cohort are hypothesis-generating, the 1000 mg/dL IgG threshold appears to be a promising signal for clinical risk stratification. Our results suggest that vigilant monitoring and individualized IgG therapy are crucial for optimizing outcomes in these high-risk pregnancies.