Being pregnant with a large baby requires increased monitoring. What are the causes and risks of fetal macrosomia? Answers from Anh-Chi TON, midwife in Paris.
The ultrasound just confirmed it: your baby is exploding all the counters! At the very top of the curves, its estimated weight is clearly above average. Your pregnancy will then be subject to increased surveillance, fetal macrosomia indeed requires close monitoring.
A baby is said to be a macrosome when he weighs more than 4 kg at birth “During pregnancy, we will speak of macrosomia when the weight of the fetus is estimated beyond the 90th percentile. Which means that only 10% of babies are overweight“, details the midwife. She specifies that it is important to base oneself on the reference curves, because the weight above the 90th percentile varies according to each gestational week.
- “Fetal macrosomia is very often linked to a complication of gestational diabetes“says Anh-Chi Ton. Among the other risk factors, we can mention
- excessive weight gain of the mother
- late pregnancy.
Baby’s weight also increases with the number of children but classically not to the point that the following babies are macrosomes. “There are also constitutional cases, for example if the father and / or mother were also macrocosms at birth“, adds the midwife.
Several tests can screen for fetal macrosomia. Before talking about ultrasound or blood tests, the clinical examination of the future mother is already an indicator. The doctor or midwife will take a close look at the uterine height and the umbilical perimeter, then will cross these results with the stage of pregnancy and body mass index from the mother. But to confirm with certainty the diagnosis, it is necessary to carry out an echography where one will linger in particular on the length of the femur, the diameter biparietal (BIP) and the transverse abdominal diameter.
Fetal macrosomia poses a risk to the baby but also to his mother.
For the baby : risk of dystocia of the shoulder during childbirth, when the baby’s shoulder remains “stuck” at the time of expulsion. It is then an emergency which can have rare but severe complications, in particular a lesion of the brachial plexus (nerve stretched during the maneuver to bring the child out), a fracture of the clavicle or the humerus. The child may also lack oxygen and suffer from neurological sequelae. In cases that remain exceptional, this can lead to the death of the child.
For the mother : Complications due to long labor or difficult childbirth such as bleeding from delivery or uterine rupture.
“If gestational diabetes screening was not done in the second trimester or if it was negative, it can be repeated after the third trimester ultrasound if a macrosomy is suspected“, explains the midwife. An additional ultrasound can also be performed around 36 or 37 weeks to re-estimate the fetal weight. It is at the end of the pregnancy that the monitoring will be even more attentive with frequent monotoring and regular ultrasound monitoring.
The CNGOF (National College of French Gynecologists and Obstetricians) recommends adapting the care and delivery method to the degree of suspected fetal macrosomia. “It is possible to consider triggering before the end of pregnancy, especially if there is an associated diabetes, to avoid that the baby is too big and that there are too important complications. It is always a unsafe delivery“, specifies Anh-Chi Ton.
“The decision to perform a caesarean will be taken in consultation with the medical team, but also according to the will of the future mother“, she adds. Cesarean section will be considered if there is a history of cesarean section, shoulder dystocia, if the estimated fetal weight exceeds 4.5 kg with associated gestational diabetes, in case of presentation by the head office, if the future mother has known in the past a torn perineum. Thanks to Anh-Chi TON, midwife in Paris