Maternal Age Effects on Pregnancy Outcomes

Maternal age has emerged as a key determinant of obstetric and perinatal health. Women of advanced maternal age (commonly defined as 35 years or older at conception) face elevated risks of pregnancy complications, including hypertensive disorders, gestational diabetes and placental insufficiency. These conditions in turn predispose to adverse outcomes such as preterm birth, small-for-gestational-age infants, fetal growth restriction and stillbirth. Conversely, very young mothers (under 20 years) may encounter challenges related to socioeconomic factors, nutritional deficits and biological immaturity. Research into the mechanisms underlying these age-related risks has illuminated the role of uterine adaptability, placental function and maternal metabolic regulation. Globally, shifting demographics—driven by deferral of childbirth and increased life expectancy—have heightened the clinical and public-health significance of maternal age. A nuanced understanding of how chronological ageing interacts with reproductive physiology is essential for risk stratification, counselling and the optimisation of antenatal care pathways.

Research from Nature Portfolio

Investigations in model organisms have revealed that impaired decidualisation of the uterine stroma underlies many age-related reproductive failures. Studies in aged mice demonstrate blunted hormonal responses in the endometrium, leading to defects in placentation and embryonic development. Crucially, transplantation into a younger uterine environment restores normal outcomes, indicating that uterine rather than oocyte ageing drives a significant proportion of adverse effects.

Analyses of human placentas from pregnancies in women aged 35 and above have identified morphological and functional alterations, including reduced placental efficiency, aberrant syncytial structure and dysregulated amino-acid transport. Complementary work in a murine model corroborates these findings, showing increased late fetal loss, lower fetal weight and diminished materno-fetal nutrient transfer with advancing maternal age.

A large retrospective cohort from a tertiary centre in China has quantified the rising incidence of pregnancy complications and adverse perinatal outcomes with age. When adjusted for parity and socioeconomic variables, risks of hypertensive disorders, gestational diabetes, caesarean delivery and low-Apgar scores increased substantially in women over 35, underscoring the need for tailored antenatal surveillance in this group.

Maternal Age Effects on Pregnancy Outcomes publication trend

The graph below shows the total number of articles in maternal age effects on pregnancy outcomes across all publications each year (not limited to Nature Index journals).

Technical terms

Advanced maternal age: Maternal age of 35 years or older at conception, associated with increased obstetric and perinatal risks.

Decidualisation: The transformation of uterine stromal cells into specialised decidual cells that support placental implantation and development.

Placentation: The formation and maturation of the placenta, critical for nutrient and gas exchange between mother and fetus.

Fetal growth restriction (FGR): Impaired intrauterine growth resulting in a fetus that falls below expected weight percentiles for gestational age.

Preeclampsia: A hypertensive disorder of pregnancy marked by elevated blood pressure and proteinuria, often leading to maternal and fetal complications.

Small-for-gestational-age (SGA): Birthweight below the 10th percentile for gestational age, reflecting potential intrauterine nutritional or placental insufficiency.

References

1. The effect of advanced maternal age on perinatal outcomes in nulliparous singleton pregnancies. BMC Pregnancy and Childbirth (2018).
2. Decidualisation and placentation defects are a major cause of age-related reproductive decline. Nature Communications (2017).
3. Placental Dysfunction Underlies Increased Risk of Fetal Growth Restriction and Stillbirth in Advanced Maternal Age Women. Scientific Reports (2017).
4. Pregnancy Outcomes in Women of Advanced Maternal Age: a Retrospective Cohort Study from China. Scientific Reports (2018).
5. Advanced maternal age pregnancy and its adverse obstetrical and perinatal outcomes in Ayder comprehensive specialized hospital, Northern Ethiopia, 2017: a comparative cross-sectional study. BMC Pregnancy and Childbirth (2020).