Andrea Cox is getting an IV of a drug called magnesium sulfate. It's because of a condition called pre-eclampsia that caused her baby to be born a month early.
"That's supposed to help protect from seizures, which can be a complication of pre-eclampsia," Cox said.
Rebekah Villarreal got magnesium sulfate, too, to help prevent early labor after she had fetal surgery to repair a spina bifida defect in her baby.
"So I wouldn't have any contractions after the surgery," Villarreal said.
Magnesium sulfate has been used for years to prevent premature labor. But now a serious side effect has surfaced: thin bones caused by calcium loss.
"A baby born with very, very thin bones -- if they have any kind of reasonably traumatic or even in a normal delivery -- if those bones are thin, they may fracture during the normal birth process," OB-GYN Dr. Michael Belfort said.
Dr. Belfort says studies showed this happened when pregnant women were given magnesium sulfate for weeks at a time. Fortunately, most of the babies recovered bone strength after birth.
At Texas Children's Pavilion for Women, they will use it for no longer than 48 hours. The FDA says to limit magnesium sulfate to no more than seven days. But it's still an important drug in certain situations.
It also is being used when babies are going to be born about 24 weeks. And those very premature babies are more likely to have cerebral palsy. They think magnesium sulfate could protect them from that.
So magnesium sulfate can be a baby's life saver or be lead to fractured bones, depending on how long it's used.
But Villarreal says it helped saved her baby.
"It was worth the risk so that I wouldn't go into labor and have the baby prematurely," she said.