Doctors are prescribing pregnant women antibiotics that may harm their developing babies more frequently than in years past, the Centre for Diseases Control (CDC) warned in a study published Thursday.
Urinary tract infections (UTIs) are common in pregnancy, especially in the first term.
Of the many antibiotics that can effectively treat UTIs, two increase the risk of brain, heart and facial birth defects in developing babies.
Yet the CDC estimates that more than 40 percent of pregnant women that get UTIs are given one of these two potentially dangerous medications to treat their infections.
The Centers for Disease Control and Prevention analyzed data on prescriptions from private insurance companies for the period between 2013 and 2015.
Of more than 480,000 pregnant women, about seven percent developed UTIs just before or during their pregnancies.
Pregnant women are more vulnerable to bladder infections because, as their bodies prepare to carry a child, their bladders expand and, for most, a certain bacteria grows more than usual, leading to more risk of bladder infections.
Doctors prescribed antibiotics to treat the infections to the majority of the women, and the researchers found that more than four in 10 women were given either sulfonamides or nitrofurantoin.
The American College of Obstetricians and Gynecologists (ACOG) issued a warning against the two antibiotics in 2011 after some research found links between the medications and major birth defects.
These included brain malformations, cleft lip and palate and heart defects.
In spite of the guidance, the new CDC study found that doctors prescribed nitrofurantoin to nearly 35 percent of the pregnant women, and sulfonamides to more than seven percent of them.
The brand-named drug Bactrim is a sulfonamide, and nitrofurantoin is also known as Macrobid.
Compared to a similar study on prescriptions written between 2002 and 2011, doctors appear to be giving women the potentially harmful antibiotics more often in recent years.
There are plenty of antibiotics that are perfectly safe for most pregnant women, including the commonly-prescribed penicillin and cephalosporin.
Every year, about 120,000 babies are born with birth defects, according the the CDC.
Evidence of the tie between antibiotics and these malformations is mixed, but convincing enough that ACOG has advised health care providers to only prescribe them if there are on other treatments available, which is rarely the case.
The CDC wrote that health care providers should ‘consider that they might be “treating for two” when prescribing antibiotics for urinary tract infections to pregnant women and women who might become pregnant in the near future.’