Four decades ago, the median age of females giving birth was 25, while today it is 30.7. Similarly, the median age of females at first birth has been pushed five years later to 29.3. The age group with the highest fertility rate (births per female) are those 30 to 34.
The average age of first-time mothers in America is now 26, while for fathers, it's 31. “One important implication of waiting to have children is the health risks that both new mothers and their infants may face when a first-time birth parent is 35 or older,” Dr. Mooney says.
an increase in the average age of first-time mothers (from 28.4 years in 2011 to 29.7 years in 2021) a decrease in smoking at any time during pregnancy (from 15% in 2009 to 8.7% in 2021)
While delivering at age 35 and older is officially considered “advanced maternal age,” Dr. Kalish notes that in reality, there's no “magic number” for being at-risk for complications. “A healthy 38-year-old could have an easier pregnancy than a 20-year-old who has multiple medical issues,” Dr. Kalish says.
A pregnancy that begins after age 35 is classified as a high-risk pregnancy because the risk of complications is higher, not inevitable. Many of the problems that occur with pregnancies after age 35 are related to health conditions that occur more often as you age.
There's more to consider about pregnancy past your mid-30s. Older women are more likely to miscarry or have a stillbirth. They have a greater chance of developing gestational diabetes, preeclampsia, and of delivering a baby who is very small.
Women who become pregnant in their 30s and early 40s can have safe, healthy pregnancies, says Ellie Ragsdale, MD, director of fetal intervention at UH Cleveland Medical Center. But they do face a higher risk of some problems.
As you get closer to 40, it's biologically more difficult to get pregnant and you may have a higher risk of miscarriage, chromosomal issues, and other pregnancy complications. But most women in their 30s will get pregnant with little trouble.
But the average age of women at first birth today (29.6) is not very different to what it was in 1938 (29.0), and fertility among women in their forties was higher at the start of WWII and during the 1940s than it was in 2010.
Male Fertility Facts
Peak male fertility is around 25-29 years old. Sperm quality begins to decline at 30. At 45, men begin to experience a significant decrease in semen volume. Older men can also take longer to conceive a child.
A gap of 3 years or more greatly reduces the chances of sibling rivalry. By this time the older child is secure in him or herself and quite independent. In addition, the mother's body is fully recovered from the challenges of pregnancy and birth of the first child.
Each woman is born with a set number of eggs. You release an egg each time you ovulate, about 14 days before you have your period. So as you get older, you have fewer and fewer eggs, and the eggs you have aren't easily fertilized by a man's sperm. All this makes it harder for you to get pregnant.
One third of all couples conceive within about 18 months after the birth of their previous child, making the median age interval between children 24-29 months. Although shorter age gaps are more common than larger age gaps, 5% of births occur with age intervals as large as 10 years.
Some studies show that while there is a higher risk of pregnancy problems in older women, their babies may not have more problems than babies of younger women. This is more likely when women get prenatal care and give birth in a healthcare facility ready to care for high-risk mothers and babies.
One study estimated a woman can have around 15 pregnancies in a lifetime. And depending on how many babies she births for each pregnancy, she'd probably have around 15-30 children. But the "most prolific mother ever," according to Guinness World Records, was Mrs. Feodor Vassilyev in 19th century Russia.
It might take longer to get pregnant.
As you reach your mid- to late 30s, the eggs decrease in quantity and quality. Also, as you get older, your eggs aren't fertilized as easily as they were when you were younger.
But when it comes to your health later in life, waiting until your 30s to give birth is better. Research shows that moms who first gave birth in their early 30s report higher energy, better fitness, and fewer aches and pains compared to moms who first gave birth in their early 20s.
In the United States, birth rates for women in their 30s are at the highest levels in three decades. However, an older mother may be at increased risk for miscarriage, birth defects, and pregnancy complications such as twins, high blood pressure, gestational diabetes, and difficult labors.
around 7 out of 10 women aged 30 will conceive within one year. around 6 out of 10 women aged 35 will conceive within one year. around 4 out of 10 women aged 40 will conceive within one year.
A woman in her early to mid-20s has a 25–30% chance of getting pregnant every month. Fertility generally starts to reduce when a woman is in her early 30s, and more so after the age of 35. By age 40, the chance of getting pregnant in any monthly cycle is around 5%.
The risk increases with the mother's age (1 in 1250 for a 25 year old mother to 1 in 1000 at age 31, 1 in 400 at age 35, and about 1 in 100 at age 40). However, 80% of babies with Down syndrome are born to women under age 35 years.
Having Babies After 35 Is Safe
And while it's true that conceiving after 35 comes with an increased risk of complications—like preeclampsia, gestational diabetes, chromosomal abnormalities, and even miscarriage or stillbirth—many people go on to deliver healthy babies.
(Identical twins come from a single fertilized egg that splits in half, while fraternal twins occur when two different eggs are fertilized simultaneously). So, how many months apart are Irish twins? It's technically possible for two siblings to be as close as 9 or 10 months apart.