More and more women are waiting longer to start a family, thanks to widely available family planning and changing social norms. These days at least one in 12 women has their first child after the age of 35.

As natural fertility declines through a woman's 30s and 40s, many are turning to in vitro fertilization, or IVF. In the last decade, the number of women over 40 who used IVF jumped more than 41 percent. With news of women giving birth after 60, fertility seems almost indefinite.

But IVF and other reproductive technologies cannot extend a woman's baby-bearing abilities forever. Even the success of assisted reproduction drops off dramatically after 40. So says a report in the journal Fertility and Sterility. [Nichole Wyndham, Paula Gabriela Marin Figueira and Pasquale Patrizio, "A persistent misperception: assisted reproductive technology can reverse the 'aged biological clock'"]

Many much-older mothers have become pregnant with donated eggs, rather than their own. The study notes that one solution for women who wish to delay pregnancy is to freeze their own eggs years ahead of time. 

But when family planning for the long term, it might be wise to realize that even the stork eventually gets too old to fly.

—Katherine Harmon

[The above text is a transcript of this podcast.]