SOOO Big

"We just had our first granddaughter! She was born six weeks early, which is really a blessing for her mom, since the baby already weighed 5 pounds."

"The Porters have just added a small blessing to their family -- actually, a rather large blessing, at 8 pounds 12 ounces."

I don't know where we have learned our fear of delivering a large baby. Sometimes babies can get rather big, and sometimes size is a consideration in determining how a baby is born, vaginally or by cesarean section. But our collective fears are exaggerated. Macrosomia (large baby) is frequently misdiagnosed; ultrasounds are notoriously unreliable for determining a baby's weight before birth.

Here are some common myths about birth weight:

• If the baby grows too much in the womb, the shoulders will become stuck during birth. This is called shoulder dystocia, and while it is a rare and very serious problem, its incidence is not connected absolutely with how much the baby weighs. "It has been established that 48 to 89% of SD occur in non-macrosomic fetuses" (Blickstein). Shoulder dystocia is unpredictable and while its likelihood increases with larger babies, it has also been reliably linked to maternal diabetes, labor induction, and the use of pain medication. Cesareans done for suspected macrosomia have resulted in dismal statistics: 100 unnecessary c-sections for one true case of macrosomia. Plus, since there is no assurance of shoulder dystocia occurring even with a large baby, performing a cesarean for the sole reason of avoiding dystocia is unsupported. Causal relationships have been established between shoulder dystocia and the following: increased maternal age, shortened first stage, prolonged second stage, maternal obesity, gestational diabetes, position of the baby during birth, labor induction, epidural use, and a long time period (8 years or more) since the previous birth.

• A larger baby will result in larger vaginal tears. Not necessarily. While there is a limit to how much tissues can stretch to allow the passage of a baby, the most important rule to avoid tearing is to slow down. Pushing too hard, too fast, and not allowing the tissues to stretch out, will almost certainly result in tears. While there is a place for episiotomies, they absolutely do not help women avoid larger tears; they create a weak spot where stress is centered and can cause more injury rather than preventing worse tearing. The best advice for avoiding tearing during birth is to take your time. My midwife told me that "Your body will not grow a baby you can't birth." I'm not certain that that is entirely and completely true, but I do believe that in the great majority of circumstances, a woman can give birth to the baby she is carrying, without it being "too big" for her. As stated on a childbirth website, "your body is designed to accomodate even a large baby."
  


• Babies gain a pound a week during the last weeks of pregnancy. I have heard this misconception many times, and I don't know where it came from. It is a lie. By the end of pregnancy babies can gain as much as one ounce per day - that equals 7 ounces per week, or less than one pound every 2 weeks. This myth leads to...

• Induction before 40 weeks will avoid the trouble of having to birth a large baby. Inducing labor carries with it so many risks that there is no evidence of improved outcomes for women thought to be carrying large babies. Inducing labor before your body is ready to give birth also increases your chances of having a cesarean.

• A large baby's head will get stuck in the mother's pelvis. True cephalopelvic disproportion (CPD) is very rare. The baby may be too large for vaginal birth in some cases, called absolute disproportion, but this is, again, extremely rare. More common causes of CPD are bad positioning of the baby, inflexible tissues of the cervix or vagina, and impatience. Another very rare cause is an abnormally-shaped pelvis (rickety or trefoil). Many women who deliver a baby by cesarean due to a diagnosed CPD will go on to vaginally birth an even larger baby, disproving the initial diagnosis.

• The average birth weight of babies has increased over time, and soon babies will become too large to birth vaginally. There has been an increase, especially noted around the turn of the century (1900, not 2000). The average birth weight suffered a giant drop leading up to around 1900, and then made steady improvements, up until the modern day, the past twenty years or so, when they seem to have levelled off. Accurate birth weight measurements were not in place until the mid-1900s. So while the first part of the statement may appear technically true, the second part is unfounded. The increase in birth weight can be attributed to better health care and prenatal care, better workforce environment, lower levels of hard physical activity, better nutrition, and education.

I am not pleased when people talk about their "giant 8-pound babies". To me, 12 pounds is large, and 8 is pretty darn close to average.

The current average birth weight for all babies is 7 1/2 pounds.

Some are larger, some are smaller. Either extreme may result from and/or cause complications. But by definition, most babies fall within the average, normal category for birth weight.

Both of the quotes above are things I have overheard in the past few months, and it made me want to jump out of my skin.

8 pounds is not huge. Anecdotally, I know many moms who say that their latest, 10-pound baby was their easiest delivery. It isn't all about weight.

Prematurity is not a good tradeoff for low birth weight.

The optimal goal is a good outcome for both mom and baby. Most of the myths I discussed are based on fact but are not exactly true. Each individual needs to research and weigh her own risks and circumstances. My intention is to clarify the truth and dispel the misleading beliefs where appropriate.