The Top Factors That Affect Your Baby's Birthweight, According To Dr. Megan Gray - Exclusive

If you've ever given birth or are currently pregnant, you're likely very familiar with the mixed bag of emotions that accompany pregnancy and the transition into motherhood. When you're carrying your baby inside your uterus, your own health directly impacts the health of your baby as well. With you and your baby being so deeply intertwined, it's only natural to have concerns about whether your labor will go smoothly, and if your newborn will be delivered at a healthy birth weight. 

Health Digest consulted with Dr. Megan Gray about common factors that contribute to a newborn's birth weight and the risks associated with giving birth to an overweight or underweight baby. Dr. Gray has over 10 years of experience as an obstetrician-gynecologist, and is a practicing OB/GYN for Orlando Health Physician Associates. As further detailed on her website, she is passionate about supporting new mothers through the trimester right after giving birth, which Harvard Health Publishing describes as the fourth trimester. Referring to the fourth trimester as the "forgotten trimester," Dr. Gray aims to spread awareness about the significance of this trimester for blossoming mothers and their newborn babies.

Every new journey into motherhood is unique. Some mothers give birth to a baby who is a healthy weight, but it's also possible to give birth to a baby who is underweight or overweight. In this exclusive interview, Dr. Gray discusses what doctors currently know about healthy birth weight factors.

What determines birth weight and what is a healthy birth weight?

There are several factors that tie into the birth weight of your baby. "Genetics, gender of the baby, maternal weight, parity, smoking status, marital status, race and gestational age of baby at delivery all impact the weight of a baby at delivery," Dr. Gray explains.

Additionally, Dr. Gray shares that two main contributors to low birth weight are preterm delivery and intrauterine growth restriction. Preterm babies are born before 37 weeks, as reported by the Centers for Disease Control and Prevention (CDC). "The CDC defines low birth weight as [less than] 2500gm," Dr. Gray says. "However, for a preterm baby, this may be a very normal birth weight based on gestational age at delivery." 

"In utero, prior to birth, estimated fetal weight based on ultrasound measurements is categorized based on percentile, ideally a baby would be somewhere around the 50%," Dr. Gray explains. And babies can also be born at an increased birth weight, falling above the 90th percentile. "A high birth weight (or macrosomia) is anything over 4000gm no matter the gestational age," Dr. Gray says. "So normal birth weight would be greater than 2500gm and less than 4000gm."

Whether a birth weight is considered normal or abnormal can depend on the baby's gestational age. For example, "If you have a baby born at 34 weeks that weighs 3500gms, that is abnormally large for a baby at that gestational age," Dr. Gray tells us. 

What are the potential health risks of having a low or high birth weight?

Being born with a low or high birth weight can have equally troublesome consequences for a baby. For underweight babies, Dr. Gray explains they may have "difficulty maintaining body temperature, difficulty maintaining blood sugar, respiratory problems (RDS), brain bleeding (intraventricular hemorrhage), [have] higher risks of infection, [and] jaundice. As the baby ages he/she may be at higher risk for developing diabetes, metabolic syndrome, and intellectual/developmental disabilities."

Additionally, it's possible to experience birth trauma if a baby is born with a birth weight larger than 4500gm. "These babies may be at risk for low blood sugars, childhood obesity and metabolic syndrome," Dr. Gray notes. Larger babies may also have an increased risk for shoulder dystocia if they have a mother with gestational or pre-gestational diabetes. Dr. Gray explains that shoulder dystocia is when "shoulders get stuck behind the mother's pubic symphysis resulting in permanent nerve damage to the baby's arm due to the way fat is distributed around the shoulders and midsection of the baby as a result of the diabetes."

Health risks in the long run

While we can't control the weight we were born at, it can help to understand some of the longterm risks associated with being born either overweight or underweight. Dr. Gray explains that sometimes birth weights can impact a person's health years down the road. "Babies at the extremes (low birth-weight/high birth-weight) are [at] a higher risk for diabetes and metabolic syndrome as well as long-term complications associated with early complications such as intraventricular hemorrhage or respiratory distress associated with low birth-weight newborns."

However, while a low or high birth weight isn't ideal, and either one can increase the potential for health problems, it's important to note that these risks don't happen to everyone. "Not all low birth-weight or high birth-weight babies will have complications immediately or in the long term," Dr. Gray shares with us.

If you would like to learn more about Dr. Megan Gray, you can visit her website at Forgotten Trimester, and follow her on Facebook, Instagram and YouTube.