Advanced Maternal Age

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Basics

Description

  • The cutoff age for advanced maternal age (AMA) is not uniformly defined.
  • Delayed childbearing is traditionally defined as pregnancy occurring in women aged ≥35 years.
  • AMA is a growing trend within high-income countries.
  • At a time when women are delaying childbearing, the availability of assisted reproductive technologies for older women has allowed women to extend their reproductive options.
  • Maternal age is the most important determinant of fertility, and obstetric and perinatal risks increase with maternal age (1).
  • After 35 years of age, fecundity decreases, and the chance of miscarriage, spontaneous abortion, pregnancy complications, and adverse pregnancy outcomes increases (2).

Epidemiology

Incidence

Recent decades have witnessed an increase in mean maternal age at childbirth in most high-resourced countries.

  • In 2014, 9% of first births in the United States were to women ≥35 years of age, which is a 23% increase from 2000 (3).
  • In the United States, there were 743 births to women ages ≥50 years in 2014, an increase from 677 births in 2013.

Prevalence
  • In 2014, 9% of first births in the United States were to women >35 years of age, which is a 23% increase from 2000 (3).
  • In 2016, the birth rate for women 45 to 49 years old was 0.9/1,000 women, the highest rate for this age group since 1963 (4).

Etiology and Pathophysiology

  • Some obstetric complications in older women appear to be related to the aging process alone, whereas others are related to coexisting factors, which are less likely to be observed in younger women.
  • Observational studies have consistently demonstrated a decline in pregnancy rates with advancing maternal age (2).
  • Cycles that result in pregnancy are less likely to progress to live births because of higher rates of aneuploidy and spontaneous abortion among older women (1,2).
  • Recent studies of AMA pregnancies identified signs of accelerated placental aging, altered nutrient transport, and vascular function compared to a control group (5).

Risk Factors

  • There are important differentials in the risk for women 35 to 39, 40 to 45, and >45 years (4).
  • For women aged 40 to 44 years, the likelihood for most adverse outcomes is increased compared with women aged 35 to 39 years (4).
  • Women ≥45 years of age are at highest risk for a broad range of adverse outcomes during delivery hospitalizations (4).

General Prevention

  • All adults of reproductive age should be aware of the obstetrical and perinatal risks of AMA, so they can make informed decisions about the timing of childbearing (1,2)[A].
  • Women not desiring pregnancy should be offered contraception and counseling.
  • Patients may minimize risks by treating preexisting conditions and should be counseled to optimize their well-being with healthy diet, exercise, and to avoid smoking.
  • Many women are unaware of the success rates or limitations of assisted reproductive technology and of the increased medical risks of delayed childbearing.

Commonly Associated Conditions

  • Maternal age is an independent factor associated with adverse pregnancy outcome.
  • AMA is reported to be associated with a range of pregnancy complications including fetal growth restriction, preeclampsia, placental abruption, preterm birth, and stillbirth (5).
    • These risks appear to be independent of maternal comorbidities.
    • The rate of spontaneous abortions, ectopic pregnancies, and stillbirths increases exponentially with age.
  • The risk of fetal aneuploidy increases with maternal age.
  • Use of assisted reproductive techniques and ovulation induction has significantly contributed to increased rate of twin and triplet births, which further contributes to complications during pregnancy (6).
  • Pregnancy risks in women >45 years have increased rates of preexisting hypertension and pregnancy complications, such as gestational diabetes mellitus, gestational hypertension, and PE (5).
  • AMA is associated with an increased risk of cesarean birth (5).

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