Most moms cringe at the idea of giving birth to a large baby, but what are the real issues? We spoke with a midwife to find out if babies are really getting bigger — and what problems this presents.
How big is too big?
There certainly isn't a "perfect" size and weight for a newborn baby, and genetics plays a big role in determining how large a baby grows before birth. What other factors affect birth weight? We spoke with Stephanie Tillman, CNM, MSN, and asked if she is seeing this trend in her practice.
"It is great that you mentioned that there is no 'perfect size' for babies, because that is exactly true," she says. "There are certainly outliers in regards to unhealthily large or small babies, but the range of healthy is vast."
Tillman shares that approximately one in ten babies born will be considered "big" — macrosomic, in medical terms — and will range anywhere from 8 pounds, 13 ounces, to 9 pounds, 15 ounces.
"Since even that is generally a large range, concerns over birth weight are also increasingly 'general' and decreasingly 'hard-and-fast,'" she adds. "Importantly, saying that one in ten babies will be born big does nothing to describe the health of that 'one' or the health of the other nine. That is to say, big does not necessarily equal unhealthy."
The relative health of a larger baby is determined by other factors than simply a high birth weight.
Are guesses accurate?
We have all heard stories of mothers who were warned that their babies were going to be huge and who went on to deliver an average-sized baby. Even with all of the modern technology at an OB-GYN's office, the most accurate way to determine a baby's weight is to deliver him.
"Truth be told, there is no positive way to know a baby's size until birth, even with the best clinical skills or ultrasound techniques, and research has shown that for most suspected big babies, their actual weight at birth was normal," shares Tillman. "Pregnancy and birth are full of surprises, and sometimes big babies — as well as small babies — are part of that package."
Rebecca Dekker, Ph.D., RN, APRN, is founder of Evidence Based Birth and has done extensive research on the issue of high–birth weight babies.
"In the U.S., most women have an ultrasound at the end of pregnancy to estimate the baby's size," she writes, "and if the baby appears large, their care provider will usually recommend either an induction or an elective C-section."
Dekker advocates for a more evidence-based approach, since many examination room weight estimates turn out to be off base.
Suspected big babies
Data from the 2013 Listening to Mothers Survey found that two out of three American women had an ultrasound in the final trimester of pregnancy to best determine the size of their baby. One-third of these women were cautioned that their babies were too big — and of these women, two out of three said their care provider discussed induction due to the large baby, and one out of three said their care provider discussed scheduling a C-section due to the suspected high birth weight.
"If a provider is concerned [about] high birth weight late in pregnancy, this concern is founded in the health of the baby for birth," says Tillman. "The provider may check records from throughout the pregnancy — including maternal weight gain, borderline values in the gestational diabetes screen or genetic testing results — none of which bear out in research to predict a large baby."
According to Dekker, concerns about a suspected big baby were the fourth most common reason for an induction (16 percent of all inductions), and the fifth most common reason for a C-section (9 percent of all C-sections).
"However, it bears repeating that suspecting a big baby — even if backed by clinical exam and ultrasound — in evidence does not show to actually predict a big baby," adds Tillman. "Medicalization of birth has drawn more attention to concerns of big babies than is warranted," she says, "and to a level that can be unhealthy for both the woman and the baby."
Actual big babies
The other side of this issue is the babies who actually are large at birth.
"If a baby is born at a higher birth weight, there are founded medical concerns for the woman's and the baby's health," shares Tillman.
She points to shoulder dystocia, which occurs when the baby's shoulders become stuck as the baby is traveling through the birth canal. Care providers can try several maneuvers in an attempt to alleviate the problem, but it can be a scary emergency situation in the delivery room.
"Concerns for long-term nerve injury and for the baby's life are real," says Tillman. "Though this event is rare, it is also completely unpredictable and has not been shown to be related solely to birth weight, as even small babies can experience a dystocia."
As for the pregnant woman, concerns about postpartum hemorrhage, perineal tears or pelvic floor dysfunction later in life have not been borne out by the evidence as related specifically to high–birth weight babies. Many of the complications of labor and delivery relate more to the method of delivery than to the baby's size.
"As mentioned above, many women's labors are being induced or surgically managed for suspected big babies, and women have [a] much higher risk of consequences from these approaches than a suspected big baby might bring them," adds Tillman.
Think it through
Is your maternal health care provider advocating for induction or C-section due to the size of your unborn baby? Be informed and do your homework in order to make an educated decision based on your individual situation. In addition to writing her article, Dekker recently launched an online class on suspected big babies, and it is a good source of information for pregnant mothers-to-be who are concerned about the size of their babies.
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