Most women expect to give birth to a 6 or 7 pound bundle of joy. But some babies exceed those expectations. Full term babies weighing over about 9 pounds fall into the 90th percentile for weight and are known as large for gestational age (LGA) babies.

Geusstimating Size

How do you know if you’re going to have a big baby? Ultrasounds can be helpful in estimating the size of a large baby, but “After the first trimester the ultrasound is less accurate on estimating weight,” points out Dr. Lisa Masterson, OB/GYN at Cedars Sinai Medical Center in Los Angeles. Ultrasounds in the third trimester can be off up to 20% when it comes to estimating weight.

Because care providers often can’t accurately estimate a baby’s size late in the pregnancy, “Don’t believe anything they tell you about the size of your baby. They’re not sure either!” points out Janet Ortegon whose son weighed 10 pounds, 6 ounces.

Where Do Big Babies Come From?

There are three general reasons why a baby might be LGA. The first is an underlying medical problem. The most common medical cause of a LGA infant is a mother with gestational diabetes. “Simply stated, glucose is the baby’s favorite fuel for growth. When maternal blood sugar is high, more glucose is available to the fetus, resulting in larger fetal weights,” explains Dr. Mark Dykowski, OB/GYN at Generations OB/GYN Center in Birmingham, Michigan. Genetic syndromes such as Beckwith-Weidemann Syndrome and Weaver Syndrome are rare, but can also cause an infant to be large.

The second and most important cause for LGA babies is the mother’s size and family genetics. “Large mothers tend to have large babies,” says Dr. Robert Baker, professor of pediatrics and Co-Director of GI/Nutrition at Children’s Hospital of Buffalo.

If a woman has already had one LGA baby, that odds that her other babies will be large increases. “Each successive pregnancy increases the infant birth weight 2.7 to 4 ounces,” explains pediatrician Dr. Deborah Campbell, professor of clinical pediatrics at Albert Einstein College of Medicine. A woman who herself was over eight pounds at birth is twice as likely to have a large baby. Boys tend to weigh more than girls. And Native American, Latino and Caucasian women tend to have larger babies than women in other ethnic groups. There is also a link to the amount of weight gained during the pregnancy. “Average weight women with a more than 30 pound weight gain are 3.3 times more likely to have a baby with a high birth weight,” says Dr. Campbell.

The third reason for LGA babies is conditions in the womb. “Since 1970 there has been a steady increase in the number of infants with [high birth weight]. This is probably ascribable to a change in the recommendations given to pregnant women,” suggests Dr. Baker. Women today are less likely to smoke or drink alcohol and are more likely to have a balanced diet and appropriate weight gain during pregnancy.

Get it Out!

Large babies can be a challenge to deliver and are twice as likely to be born by c-section because of difficulty fitting through the birth canal. Shoulder dystocia occurs when the baby’s shoulders can’t fit through the birth canal and get stuck, even if the head makes it out.

Because vaginal delivery of a LGA baby can be difficult and may take longer, these babies can have fractured clavicles, bruising and breathing problems. “Many women do deliver healthy large babies vaginally, so the obstetrician should discuss this with mom and dad if she suspects a big baby. Shoulder dystocia can impair delivery, necessitating an emergent c-section, or result in a fractured clavicle (that heals easily). The more significant injury is brachial plexus injury – injury to the nerves that travel through the neck to the arm. Although this injury can resolve on its own, it can be permanent,” warns Dr. McCoy.

To improve chances for a vaginal birth, women need to watch weight gain, exercise and “modify your diet to one that is high in protein and low in fat,” suggests Dr. Lorraine Chrisomalis, assistant clinical professor of obstetrics at Columbia-Presbyterian Eastside in New York. She also recommends that patients with LGA babies “be monitored very closely during the labor. If the patient has any labor abnormalities such as a prolonged second stage, an arrest of dilatation or an arrest of descent, a caesarean section needs to be considered.”

Debi Salanitro delivered her 9 pound 12 ounce baby vaginally, but discussed her options with her care provider in advance. “My doctor agreed to let me tear instead of performing an episiotomy, as I felt I would heal much better from a soft tissue tear rather than a cut muscle.”

Vaginal birth may not always be best. “Hindsight being 20/20 I wish they had done a section on me,” shares Catherine Diede, whose 9 pound 7 ounce son had to be intubated after a difficult delivery since he was not breathing, had meconium aspiration and developed pneumonia and sepsis. “I had an episiotomy all the way back to the rectum so recovery was difficult for me.” Your care provider can help you weigh the risks and benefits of vaginal birth.

Heft Doesn’t Equal Health

Many parents of LGA babies assume their babies are healthier simply because of their size. “I think my babies were more hearty, less flimsy,” recalls Dawn Rice, who delivered an 11 pounder.

Jill Fitzsimmons, who delivered a 9 pound 9 ounce baby, remembers, “The other smaller newborns I ran into seemed so frail. There’s something about a bigger newborn that makes you feel more secure, like they won’t get as sick or aren’t as fragile.”

The experts don’t agree. Dr. McCoy explains, “All other things being equal (maternal health, gestation, normal delivery), large babies are also equal to average size babies” when it comes to health.

In fact, large sized babies are susceptible to particular problems such as breathing difficulties. According to Dr. McCoy, “If the baby is large because of maternal diabetes, that may delay lung maturation” and “if the baby is delivered by c-section, that may be associated with some transient respiratory distress.”

Another concern is blood sugar levels. LGA babies, whether their mother has diabetes or not, are prone to low blood sugar after delivery. “Babies over about 8 and a half pounds should have their blood sugar checked for the first few hours. Early signs are usually jitteriness and sometimes excessive sleeping,” details Dr. McCoy. If this does occur, “we’ll recommend a feed. Ideally if the baby breastfeeds in the delivery room, it may prevent the sugar from dropping. Sometimes doctors will recommend feeding the baby every two to three hours for the first day to keep the sugar from falling.”

Feeding Frenzy

It seems to make sense that if you have a bigger baby, he or she is going to need more milk since there’s just more baby to feed. “They do need more calories and this can mean more frequent feeds...The larger the baby, the more milk that will need to be ingested,” says Dr. Baker. However, he points out that “all babies, including large babies, do very well at self-regulating.”

Despite this, some moms have found that they couldn’t keep up with their large infants’ appetites. “Regular formula bottles were not filling enough for him, so the doctor agreed to spoon feeding of a few teaspoons of cereal a day as of 5 weeks of age. Alex did very well with this and certainly seemed more satisfied and wouldn’t cry for a bottle as often,” says Salanitro.

“Those babies were hungry. I wasn’t waiting until they were six months old,” says Fitzsimmons, who started cereal at 3 ½ months for her largest baby.

April O’Herron’s 9 pound 8 ounce baby was overly hungry, so she “gave her rice cereal in her formula and cut the nipples on the bottles wider. “

Jacqueline Turbitt’s daughter weighed 9 pounds, 12 ounces and wasn’t sleeping more than four hours between night feedings “my doctor…suggested to start the cereal sooner rather than later.” Other parents report offering their babies small amounts of water or sugar water to stave off hunger.

The official word on supplementing is a bit different though. “Normal babies, whether large or small, do not need extra water or sugar,” explains Dr. Baker “It is normally recommended to start solid foods between 4 and 6 months when the baby is developmentally ready.” Solids are added to provide nutrients the baby cannot get from breast milk or formula, not because of hunger or size. Talk to your pediatrician if you feel that your baby is not getting enough calories.

Big and Beautiful

Your LGA baby will stand out in the nursery. “Large infants are often perceived to look and behave as if they are more mature than their normal birth weight counterparts,” says Dr. Campbell.

Diede’s son certainly did. “He had jaundice and the nurses were calling him the Jolly Yellow Giant. He looked like a three month old and even sounded like one. His cry wasn’t a newborn cry at all.”

O’Herron’s daughter also seemed different, “Her face seemed to have more developed features than the other newborns.”

Sandra Ray Midland, whose son weighed 9 pounds 13 ounces, recalls, “When my son was born he had rolls of fat on his thighs and just looked to me like a one month old baby.”

Katherine Muzyczka’s 9 pound 15 ounce son “seemed more alert and ‘finished’ somehow…It made it much easier to connect with him, I think. He seemed like more a person.”

Some parents believe their infants slept better because they were bigger, “She was sleeping through the night in a week after getting home,” reports O’Herron.

The experts back this up to some degree. “LGA babies, specifically infants of diabetic mothers, tend to be more difficult to arouse,” agrees Dr. Campbell.

LGA babies sometimes seem to have better neck control. “My son was never a ‘newborn’. My mom held him and he raised his head off her shoulder and looked her straight in the eye,” remembers Sandy Pickett who delivered a 10 pounder.

Dr. McCoy disagrees with this though, “I believe that many parents believe the head control is exceptional, when in fact it is average.”

Lose the Layette

When you bring home a LGA baby, you may be surprised to find that your newborn layette is totally useless. “My son couldn’t wear newborns, though we’d gone out and bought bunches,” says Pickett.

Ray had a similar problem. “We never did use the newborn diapers. We went straight to the size one diapers.”

If you know you’re carrying a LGA baby, don’t toss the layette. Keep the price tags on all newborn size until the baby arrives and you can see what fits, but buy size three months as well. Have both newborn and size one diapers on hand, but don’t open the packages (no matter how much you want to fill that cute diaper dispenser) so you can return them if necessary.

Big Baby, Big Adult?

Your large newborn looks adorable with all those extra rolls of fat, but does this mean he or she is always doomed to be the biggest kid on the playground? “It is generally believed that birth weight is a reflection of genetics and maternal nutrition during pregnancy. Therefore, birth weight does not reflect adult obesity,” explains Dr. Baker. However, he points out that a recent study found that “obesity tracks down to at least 6 months,” meaning that overweight 6 month olds are more likely to be overweight as adults than smaller babies.

Dr. Campbell cautions that, “a pattern of rapid weight gain during the first four months of life is associated with an increased risk of overweight status at 7 years of age”. Your child should have a pattern of regular, gradual weight gain in the first year.

Parents of LGA babies may worry that their children are more likely to develop diabetes, but the risk is not as high as you might suspect. According to Dr. Campbell, low birth weight babies (under 5.5 pounds) actually have a higher risk for diabetes (40%) while babies weighing over 9.5 pounds have only a 14% risk.

Size Doesn’t Matter

If you have a LGA baby you might get tired of comments like “He’s so huge!”, “You must have had diabetes” or “That’s not a baby, it’s a full grown adult.” Some people assume you overate while pregnant. Even when it comes to babies, the prejudice is that thinner is better. However, if you have one or are expecting one, you know that LGA babies are beautiful. “Just because a baby is big, doesn’t mean anything is wrong,” opines Muzyczka.

Often, the size of your baby is not related to what you did or didn’t do while pregnant. “I think I just grew big babies,” says Turbitt. “My OB/GYN said I had a predisposition to have big babies. I only gained 6 pounds when I was pregnant and had a large baby. I don’t think there was any way for me to have a small baby. I really think genetics had something to do with it. I was proud to have a large baby.”