Twins: The Fetal Paradox

In 2004, Danielle Decrette went in for in vitro fertilization. It wasn’t her first time—she and her husband had a 3-year-old daughter conceived through IVF—and she knew what she was getting into. Just as he had four years before, Decrette’s doctor stimulated her with hormones, extracted her eggs from her ovaries, fertilized them with sperm in the lab and placed the resulting embryo in her uterus. But this time the process failed. So the doctor decided to transfer two embryos in the next round to increase her odds of getting pregnant.

“You know you could have twins,” the doctor warned her before the procedure. Decrette says she “freaked out…I just wanted one more baby.” But because it seemed like her best chance at another child, she decided to do it anyway. Her twin preemies were born two months early, underweight at 3.5 pounds each, after a difficult pregnancy requiring an unusually high amount of time on bed rest.

Despite their premature birth, her twin daughters are now “perfect,” she says. “It’s such a blessing to have them.” But...