Advanced Maternal Age and Stillbirth Risk in Nulliparous and Parous Women.

Area of Science:

• Reproductive Health
• Perinatal Epidemiology
• Maternal-Fetal Medicine

Background:

• Advanced maternal age (AMA) is a growing concern in obstetrics.
• The association between AMA and adverse pregnancy outcomes like stillbirth requires further investigation across different parities.

Purpose of the Study:

• To examine the relationship between advanced maternal age and stillbirth risk.
• To assess this association across varying numbers of previous births (parity).

Main Methods:

• Population-based registry study in Sweden (1990-2011) analyzing 1,804,442 singleton pregnancies.
• Logistic regression analyses adjusted for sociodemographic factors, lifestyle, and obstetric history.
• Stratified analysis by parity and investigation of low-risk subgroups (high education, normal weight non-smokers).

Main Results:

• Stillbirth rates increased with maternal age, from 0.27% (25-29 years) to 0.53% (≥40 years).
• AMA significantly elevated stillbirth risk in first births (approx. 25% increase at 30-34 years, doubled at ≥35 years).
• In parous women, AMA-associated risk was mitigated in highly educated groups and in normal-weight non-smokers, with specific age thresholds for increased risk in second and third+ births.

Conclusions:

• Advanced maternal age is an independent risk factor for stillbirth in women having their first child (nulliparous).
• This age-related stillbirth risk appears diminished or absent in women with previous births (parous).
• Potential physiological adaptations from prior pregnancies may offer protection against age-related stillbirth risks.