The fertility of males and females declines with age. Advancing age can make it more difficult to conceive and increase the risk of pregnancy complications.

This article looks at how age can affect fertility, the likelihood of pregnancy complications, and life with a newborn.

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The fertility of males and females decreases with age.

For women, fertility peaks in their late teens and early 20s, and it can start to decline by age 30.

According to the American College of Obstetricians and Gynecologists (ACOG), around 1 in 4 healthy women in their 20s or early 30s become pregnant per menstrual cycle, while the same is true for 1 in 10 healthy women by the age of 40.

This is because, as a woman ages, the supply and viability of eggs declines. Also, hormone levels can shift, making it more difficult for the body to support healthy pregnancy.

In addition, age may correspond with an increased risk of conditions such as uterine fibroids and endometriosis. Both of these can affect fertility.

Endometriosis involves tissue similar to uterine lining growing beyond the uterus. This tissue may block off or change the shape of reproductive organs, making it more difficult for sperm to reach an egg.

The condition may also cause the immune system to attack an embryo. However, many women with endometriosis do conceive and carry babies to term.

Age can affect male fertility also, but the decline in males is less predictable than it is in females.

In addition, age of over 45 years in a male can make conceiving more difficult. It can also increase the likelihood of pregnancy complications.

Specifically, older paternal age can increase the risk of:

  • pregnancy loss
  • genetic abnormalities
  • cleft palate
  • gestational diabetes
  • preeclampsia
  • preterm birth
  • low birth weight
  • heart disease
  • seizures

Advancing parental age can increase the likelihood of congenital abnormalities and pregnancy loss.

Congenital abnormality

According to the Centers for Disease Control and Prevention (CDC), 1 in 33 babies born in the United States has a congenital abnormality.

A 2015 study found that women aged 40 or older are more likely to give birth to newborns with congenital abnormalities, including:

  • craniosynostosis, in which the skull fuses prematurely
  • hypospadias, in which the urethral opening forms on the underside of the penis
  • esophageal atresia, in which the esophagus does not connect to the stomach

Maternal age can also influence the likelihood of giving birth to a baby with Down syndrome.

According to the CDC, about 1 in 700 infants born in the U.S. has Down syndrome. It involves having 47 chromosomes instead of the usual 46. This extra chromosome can affect the mental and physical development of the baby before and after births.

The chart below describes how maternal age influences the likelihood of giving birth to a baby with Down syndrome:

Maternal ageChance of Down syndrome
20 years1 in 1,480
30 years1 in 940
35 years1 in 353
40 years1 in 85
45 years1 in 35

Pregnancy loss and stillbirth

Conceiving later in life can also increase the risk of pregnancy loss. A 2019 study of women in Norway found that, while the overall rate of miscarriage was 12.8%, the rate among women aged 45 and older was 53%.

It is important to keep in mind that a range of factors influences the risk of pregnancy loss. The authors of the above study identified previous pregnancy loss and previous pregnancy complications as influential risk factors.

The risk of stillbirth also increases with maternal age. The figures below come from a 2015 population-based study in Sweden:

Maternal ageRisk of stillbirth
25–29 years0.27%
30–34 years0.31%
35–39 years0.40%
40+ years0.53%


Preeclampsia is a condition characterized by high blood pressure, and it is a leading cause of maternal death and infant illness. ACOG note that the characteristic rise in blood pressure typically begins after the 20th week of pregnancy.

Hypertensive disorders, including preeclampsia, affect 10% of pregnancies worldwide. The risk of preeclampsia is higher among pregnant women who are over 40.

Anyone who experiences symptoms of preeclampsia should seek emergency medical aid. Some of these symptoms include:

  • swelling in the face and hands
  • a decrease in the frequency and amount of urine
  • shortness of breath
  • irritability
  • changes in vision, such as increased sensitivity to light or seeing flashes of light
  • weight gain of 3–5 pounds in 1 week
  • headaches
  • abdominal pain
  • nausea
  • vomiting

While the risk of pregnancy complications increases after age 35, many women in this age group have healthy pregnancies.

According to ACOG, if women older than 35 have been trying for pregnancy, with no results, for at least 6 months, they may benefit from seeing a fertility specialist.

Also, it may be a good idea for any woman older than 40 to have an evaluation before trying to conceive.

A fertility specialist may test hormone levels, recommend ways to increase fertility, and provide treatment, if necessary.

For anyone trying to conceive, proper prenatal care is essential.

If a woman is having difficulty becoming pregnant or would like to delay pregnancy, in vitro fertilization (IVF) or freezing eggs may be helpful options.

IVF involves combining sperm with eggs outside the body. If an embryo develops, a woman may choose to have it implanted or frozen and stored.

Another option is oocyte cryopreservation — freezing and storing eggs for use at a later date.

These alternatives can be expensive, however, and some insurance plans do not cover the cost.

In males and females, advancing age can reduce fertility and increase the risks of pregnancy complications. The reduction in fertility is more difficult to predict in males than it is in females.

As a woman ages, the number of eggs declines, as does their viability. For these reasons, some women decide to freeze their eggs or pursue IVF.

Anyone older than 35 who is having difficulty becoming pregnant may benefit from seeing a fertility specialist. They can describe any issues affecting fertility and provide guidance and treatment, if necessary.

ACOG recommend discussing any reproductive plans with a gynecologist and revisiting these plans annually.