Hilary Swank is pregnant at 52, and the news has turned attention to what age means for fertility and pregnancy. The Oscar winner announced in a 14 October Instagram video that her third baby is due at the end of the year.

Swank has twins Aya and Ohm, born in 2023, and has said she froze her eggs 10 years before that pregnancy. The announcement did not include medical details, and the research cited here is not specific to her.

How Age Changes Fertility

Age is the single most important factor affecting a woman's fertility, and good health does not override it, according to the Victorian Government's Better Health Channel. A woman is born with all the eggs she will ever have, and those eggs age with her.

Women in their early to mid-20s have a 25% to 30% chance of getting pregnant each month. Fertility slowly declines in the early 30s, speeds up after 35 and falls to roughly 5% per cycle by 40.

Pregnancy becomes highly unlikely by 45 but remains possible until menopause, according to Johns Hopkins Medicine. Fertility factors are specific to each person, says reproductive endocrinologist Vasiliki Moragianni.

She recommends an infertility evaluation after six months of trying for women 35 or older. For those over 40, a more immediate evaluation may be appropriate.

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IVF, Donor Eggs and Egg Freezing

It is a common misconception that IVF can overcome the effects of age. In Australia, live birth rates per complete IVF cycle are 43% for ages 30 to 34, 31% for 35 to 39 and 11% for 40 to 44.

Donated eggs from a younger woman improve older women's chances of a baby. Egg freezing, which Swank has said she did, may help preserve fertility, but no technique can guarantee it.

Pregnancy Risks in Later Life

Miscarriage, gestational diabetes, preterm birth, stillbirth and pre-eclampsia are among the risks that rise with maternal age. Chromosomal abnormalities and caesarean delivery are also more likely.

Although pregnancy complications become more common with age, many people in their late 30s and early 40s have healthy pregnancies. Individual outcomes depend on factors including overall health, medical history and pregnancy complications.

A retrospective study in the Journal de Gynécologie Obstétrique et Biologie de la Reproduction compared 361 women aged 43 or older with 361 aged 25 to 35 between 2008 and 2010. The research took place at a level 3 maternity unit.

Caesarean delivery occurred in 43.5% of the older group versus 21.7%, while preterm delivery reached 18.4% versus 6.5%. The researchers concluded most women with a spontaneous singleton pregnancy at 43 or older have an uneventful outcome.

Donor-Egg Pregnancies After 50

A case series by researchers at Columbia University Medical Center, published in the American Journal of Perinatology in 2012, followed 101 women aged 50 and older who conceived through donor-egg IVF. All were medically screened first.

Their rates of hypertensive disorders and gestational diabetes were statistically similar to those of recipients aged 42 or younger. Caesarean delivery was high at 81% of singleton births and 100% of multiples.

The researchers concluded these women face high risks of maternal complications, but at rates similar to younger recipients. Swank's announcement did not say how she conceived, so the findings do not describe her pregnancy.

Delivery Timing and Care Advice

Delivery at 39 weeks is recommended for well-dated pregnancies when the mother is 40 or older, because stillbirth and newborn health risks rise beyond that point. For ages 35 to 39, timing should be individualised.

Early and regular antenatal care is very important, especially for those at higher risk because of age. Dizziness, shortness of breath, fever or chills, or heavy vaginal bleeding warrant immediate medical care.

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Frequently Asked Questions

  • How does age affect a woman's fertility?
    Age is the most important factor affecting a woman's fertility, with fertility declining as a woman ages.
  • What are the chances of getting pregnant in different age groups?
    Women in their early to mid-20s have a 25% to 30% chance per month, which declines to 5% per cycle by age 40.
  • Can IVF overcome age-related fertility decline?
    IVF cannot fully overcome the effects of age, but donor eggs from younger women can improve chances.
  • What are the risks of pregnancy in later life?
    Risks include miscarriage, gestational diabetes, preterm birth, stillbirth, and chromosomal abnormalities.
  • What is recommended for delivery timing in older mothers?
    Delivery at 39 weeks is recommended for mothers aged 40 or older to reduce stillbirth and newborn health risks.