More mothers are waiting until later in life to have children, but pregnancy after 50 is still quite rare.
A woman’s fertility begins to decline in her early 30s. After age 35, her number of viable eggs starts to fall more quickly.
Women are born with a set amount of follicles – between one and two million – or immature eggs.
These develop at different rates. Some follicles never release an fully-fledged egg, but each month the ovaries release one egg to wait for fertilization in the uterus.
Most women only ovulate around 450 eggs over the course of their lives, so by their late 40s, most have run out and start to head toward menopause.
Menopause begins around age 51 for the average woman, at which point pregnancy becomes impossible.
However, even as fertility is declining among American women (and men) overall, one group is having a few more babies than they did in the past: older women.
The birthrate among women between 45 and 49 – the oldest group that the Centers for Disease Control and Prevention tracks – went up by 0.1 percent between 2016 and 2017.
In 2013, an estimated 677 American women over 50 gave birth, marking a 370 percent increase over the 144 such births in 1977.
So far, an Indian woman believed to be in her 70s who had a baby boy in 2016 is thought to be the oldest to give birth, though a 66-year-old holds the official record.
Celebrities too, have made headlines for having in their later years, including Janet Jackson who had her son, Eissa Al Mana, at age 50.
A growing number of women choose to freeze their eggs – which decline in quality with age – while they are younger, use IVF, surrogates or donor eggs in order to have children at more advanced ages.
But pregnancy after peak fertility can come with risks.
Older women are more likely to develop high blood pressure, preeclampsia, diabetes and heart problems, so most doctors screen them carefully if they are trying to conceive.
If women in this age group do get pregnant, doctors will continue to monitor them closely as a precaution, but they can certainly have healthy pregnancies, and a growing number are doing just that.