Most suspected large babies turn out to be normal-sized newborns—leading to a lot of unnecessary inductions and planned C-sections. So why does this keep happening?
If you were told at the end of your pregnancy that your baby might be well over eight pounds, you'd probably freak out a little about giving birth, right? A new study published in Maternal and Child Health Journal found just that—and this unfounded fear leads to birth interventions, including inductions and planned C-sections, that were never needed in the first place.
Why size matters
Researchers from the Boston University School of Public Health and Medicine looked at answers from a national survey of pregnant women without a prior Cesarean and compared them to the actual labor and delivery outcomes. Nearly one-third of the women were told by their doctors that they had a suspected large baby (SLB). But, only one in five women who were told so actually had a baby with an excessive birth weight, a condition called fetal macrosomia in which the newborn is more than 8 pounds, 13 ounces. The rate of birth interventions for the SLBs, however, was much higher. Those women were nearly five times as likely to ask for or plan a C-section, twice as likely to try to self-induce labor, and twice as likely to have medical inductions—regardless of what the baby's size actually turned out to be.
The study didn't specifically look at whether the mothers or their doctors made the ultimate decision for intervention, but study co-author Eugene Declercq, Ph.D., a professor of community health services, says that interventions for SLBs is the outgrowth of several trends. "One, more ultrasounds and a growing tendency to use them to estimate fetal weight with providers perhaps thinking they're more accurately predictive than they really are," he tells Fit Pregnancy. "Two, providers feeling an obligation that they have to tell mothers about every possible risk—in that way they can't be accused of failure to inform. Three, mothers wanting to know about everything that could happen. None of that is sinister, but if the information isn't conveyed in the right way, the result can be an undermining of a mother's confidence in her ability to give birth." Patients' feelings may then influence doctors' decisions about delivery.
The problem stems from the fact that diagnosing baby's size during pregnancy via ultrasound is often not very reliable, but providers are increasingly using it for that purpose. "Ultrasonogrophy has improved a great deal over time, but it remains an imprecise science, particularly in estimating weight," Declercq says. "There's a human element to it as well. If there's a close call and a clinician doesn't mention it to a mother and a problem arises later, the clinician can be called to account. If they do mention a potential problem and it doesn't occur, few people will complain."
A further irony is that bigger babies tend to fare better during birth, so less intervention may be needed anyway. "A larger baby is typically good news since larger babies are usually healthier. There is greater risk with small babies than large," Declercq says. "If a baby isn't overly large [actually macrosomic], it doesn't have to mean a mother will have trouble giving birth vaginally." Plus, he says, the rate of large babies in the U.S. has actually been declining—although concerns about them appear to be on the rise.
Should you prepare for a big baby?
What should you do if you doctor tells you have an SLB? First: Don't panic. If you're worried about a difficult labor, seek support from your doctor and other women who've given birth. Whatever you do, don't push to induce early or have a C-section before full-term, says the American College of Obstetricians and Gynecologists, because babies born before they're ready are at risk for complications, including respiratory distress. It can be scary to be faced with the possibility of delivering a large baby, but your doctor should closely monitor you during labor to decide when intervention is, in fact, needed.
Declercq says the onus is on health care providers to make sure information is being conveyed to patients in the best way, and hopes that this study will affect how that's done. Doctors should "consider the benefits and problems associated with conveying the message of a potential large baby to the mothers," he says. "It has the potential of undermining a mothers' confidence in herself, so she [should] get the message in a way that isn't alarming."