Very young and advanced maternal age strongly elevates the occurrence of nonchromosomal congenital anomalies: a systematic review and meta-analysis of population-based studies

BACKGROUND: Nonchromosomal congenital anomalies (NCAs) are the most common cause of infant mortality and morbidity. The role of maternal age is well known, although the specifics are not thoroughly elucidated in the literature. OBJECTIVE: To evaluate the role of maternal age in the incidence of NCAs and to pinpoint age groups at higher risk to refine screening protocols. STUDY DESIGN: A systematic review and meta-analysis were conducted following the PRISMA 2020 guidelines and Cochrane Handbook. Searches were performed on October 19, 2021, across MEDLINE (via PubMed), Cochrane Library (CENTRAL), and Embase. Population-based studies assessing the impact of maternal age on the incidence of NCAs in pregnant women were included, without restrictions on age range, country, or comorbidities. A random-effects model was used for pooling effect sizes, considering the heterogeneity across studies. RESULTS: From 15,547 studies, 72 were synthesized. Maternal age >35 showed an increased NCA risk (risk ratio [RR]: 1.31, confidence interval [CI]: 1.07-1.61), rising notably after>40 (RR: 1.44, CI: 1.25-1.66). The latter changes to 1.25 (CI: 1.08-1.46) if the co- occurrence of chromosomal aberrations is excluded. Specific anomalies like cleft lip/palate (>40, RR: 1.57, CI: 1.11-2.20) and circulatory system defects (>40, RR: 1.94, CI: 1.28-2.93) were significantly associated with advanced maternal age. Conversely, gastroschisis was linked to mothers <20 (RR: 3.08, CI: 2.74-3.47). CONCLUSION: The study confirms that both very young and advanced maternal ages significantly increase the risk of NCAs. There is a pressing need for age-specific prenatal screening protocols to better detect these anomalies, especially considering the current trend of delayed childbearing. Further research is required to fully understand the impact of maternal age on the prevalence of rarer NCAs.