If you're told the fetus measures ahead or behind schedule, try not to worry. It usually just means an ultrasound or further testing is needed. The fetus is more than likely developing perfectly. Talk to your healthcare provider if you have any concerns about your fundal height or the size of the fetus.
If a baby is too large to fit through the birth canal easily, delivery can be difficult. If ultrasound exams during pregnancy show a baby is very large, your healthcare provider may recommend early delivery.
Genetic factors and maternal conditions such as obesity or diabetes can cause fetal macrosomia. Rarely, a baby might have a medical condition that makes him or her grow faster and larger. Sometimes it's unknown what causes a baby to be larger than average.
A pregnant belly size that is larger than expected could suggest that the fetus is growing larger than expected and may be at risk for macrosomia, which is diagnosed in babies who weigh more than 4 kilograms (8.8 pounds) at birth.
A toddler's potbelly is nothing to worry about unless the swollen belly is accompanied by other symptoms such as abdominal pain, fever, or vomiting. A potbelly should also be evaluated by a physician if the swollen belly appears suddenly, or the child exhibits a short stature.
Some reasons the fetus may measure ahead or large for gestational age are: Your due date is wrong. You have uterine fibroids. You have a BMI of over 25 (have overweight or obesity).
The vernix coating on your baby's skin is beginning to be absorbed. Starting in week 36, your baby gains about half a pound and grows half an inch a week. Many babies turn head-down and stay in that position for birth.
Most of the time, there's a harmless explanation. Maybe your due date is off by a few days or a week (it's pretty common for doctors to change due dates). Your baby could be in a funny position or sitting high in your uterus, and that's throwing the tape measure off.
If your midwife or doctor suspects your baby will be big, she may recommend that your labour is induced early.
Vaginal birth is still recommended is your baby is estimated to weigh less than 5,000 g (10 lbs) if you don't have diabetes. If your baby is estimated to weigh more than 4,500 g (8.4 lbs), and your labor stalls in the active stage or the baby doesn't descend, this is an indication for cesarean delivery.
Possible reasons for measuring large:
Your due date was wrong. You're carrying twins or more. You have too much amniotic fluid. Baby is especially high in the uterus.
It is possible for gestational age to be inaccurate by up to 2 weeks, even with an accurate LMP date confirmed by other tests.
It's actually very common for a slight difference in weeks to exist between your gestational age and your baby's fetal age. It happens because there is a natural range of sizes for a fetus at every stage of pregnancy. Just as adults come in different shapes and sizes, so too do babies.
The baby is still growing rapidly and could gain as much as an additional two pounds during the last four weeks of pregnancy.
A father's genetic code influences the weight of a baby at birth, according to a new study led by the UCL Institute of Child Health (ICH).
Average baby weights
The average weight of a baby born at 37–40 weeks ranges from 5 lb 8 oz to 8 lb 13 oz. This is 2.5 to 4 kg. At delivery, experts consider a low birth weight to be less than 5 lb 8 oz, or 2.5 kg.
Ultrasound is not very reliable for estimating fetal weight near term. For a 9-pound baby, an ultrasound's predictive accuracy is typically 15 to 20 percent off. Which means we may over- or underestimate by more than a pound.
Ultrasounds in Later Pregnancy
As pregnancy progresses, the accuracy of an ultrasound for predicting due dates decreases. Between 18 and 28 weeks of gestation, the margin of error increases to plus or minus two weeks. After 28 weeks, the ultrasound may be off by three weeks or more in predicting a due date.
A normal cycle can be between 21 to 35 days, and some people can even have cycles that range outside of that. Regularity isn't that common, so there's a fair chance that the calculation will be off, but the last menstrual period measurement is still used because it's considered fairly reliable most of the time.
Between 22 0/7 weeks and 27 6/7 weeks of gestation, ultrasonography dating has an accuracy of ± 10–14 days 19.
LGA babies have birthweights greater than the 90th percentile for their gestational age, meaning that they weigh more than 90 percent of all babies of the same gestational age. The average baby weighs about 7 pounds at birth. About 9 percent of all babies weigh more than 4,000 grams (8 pounds, 13 ounces).
The doctor has to guess on the conception date. In order to do so the doctor guesses the time of conception by utilizing the date of the last menstrual period. This day can be wrong by up to 2 weeks.