Gestational diabetes affected 16.4 % of women who gave birth in France in 2021, compared with 10.8 % in 2016. It is one of the most striking findings of the Enquête nationale périnatale (National Perinatal Survey), published on 6 October 2022 by Inserm (the French National Institute of Health and Medical Research) together with Santé publique France and DREES. In other words, one pregnancy in six is monitored for raised blood sugar that appeared during pregnancy. This article brings together the official figures, how screening works and what the diagnosis actually changes for the baby, before and after birth.
What is gestational diabetes?
The Assurance Maladie (French national health insurance) defines it as a rise in blood sugar that appears during pregnancy and disappears, at least temporarily, after delivery. It is neither type 1 diabetes nor pre-existing type 2 diabetes, although previously undiagnosed diabetes may come to light at this point. Pregnancy hormones make insulin less effective; in some women, the pancreas cannot compensate and sugar builds up in the blood.
Gestational diabetes: the official figures in France
The Enquête nationale périnatale (ENP) surveys all women giving birth in France during a given week. The 2021 edition covered 13,631 births to 13,404 women. Its findings on gestational diabetes and the factors associated with it should be read together.
- Frequency: 16.4 % of women in 2021, compared with 10.8 % in 2016 – an increase of more than half in five years.
- Maternal age: 19.2 % of mothers were aged 35 to 39 (17.2 % in 2016) and 5.4 % were 40 or over (3.9 % in 2016).
- Weight before pregnancy: 23.0 % of women were overweight (19.9 % in 2016) and 14.4 % were living with obesity (11.8 % in 2016).
- Caesarean section: 21.4 % of births in 2021.
- Average birth weight: 3.264 kg in 2021, almost unchanged from 2016 (3.251 kg).
The rise in frequency is partly explained by changes in the risk factors – age and weight – and partly by more systematic screening since the 2010 recommendations. The ENP cannot separate these two effects.
Who is screened, and how?
In France, screening is targeted: it is offered to women who have at least one risk factor. The Assurance Maladie lists five.
- Aged over 35.
- Body mass index of 25 kg/m² or more.
- Diabetes in a first-degree relative (parent, brother, sister).
- Gestational diabetes in a previous pregnancy.
- Having previously given birth at term to a baby weighing more than 4 kg.
The two stages of screening
A fasting blood glucose test is carried out in the first trimester, as part of the early pregnancy check-up. Then, between the 24th and 28th week of amenorrhoea (counted from the last period), an oral glucose tolerance test (OGTT) is performed. The woman drinks 75 g of glucose, and her blood glucose is measured while fasting, then one hour and two hours later. A single value at or above the thresholds is enough for a diagnosis: 0.92 g/l fasting, 1.80 g/l at one hour, 1.53 g/l at two hours. These thresholds come from the recommendations of the Collège national des gynécologues et obstétriciens français (the French college of obstetricians and gynaecologists) and the Société francophone du diabète, published in 2010.
What are the consequences for the baby?
Excess sugar crosses the placenta, but insulin does not. The foetus then produces large amounts of its own insulin, which explains the two main consequences described by the Assurance Maladie.
Macrosomia
A birth weight of more than 4 kg for a baby born at term. It increases the risk of difficulties during delivery and the likelihood of a caesarean, which may be needed above an estimated 4.2 kg. Our article on the caesarean rate in France puts this figure in context.
Neonatal hypoglycaemia
At birth, the supply of sugar from the mother stops abruptly, while the newborn keeps producing a lot of insulin. The baby's blood sugar is closely monitored, particularly if the mother received insulin or if the birth weight is abnormal. Feeding starts as soon as possible after birth, then every two to three hours, to prevent drops in blood sugar. This is one of the reasons why first breastfeeds or first bottles are offered so early on the maternity ward.
And in the longer term?
Exposure to high blood sugar during pregnancy is being studied as a factor in later excess weight in children, but the Assurance Maladie does not present it as an established consequence in its pages for parents. The usual monitoring of weight and growth, described in our article on excess weight in young children, applies without any special measures. Once the first few days of monitoring are over, a baby born after a pregnancy with well-controlled gestational diabetes has the same needs as any other. Sleep, suitable feeding, floor time to move about: these are the essentials highlighted by the first 1,000 days.
How does the pregnancy continue after diagnosis?
Treatment is based first on diet and physical activity, with self-monitoring of blood glucose several times a day. If the targets are not met, insulin is prescribed; oral diabetes medicines are not used during pregnancy in France. The blood glucose targets in the 2010 recommendations are below 0.95 g/l fasting and below 1.20 g/l two hours after a meal.
Delivery proceeds normally if the diabetes is well controlled. It may be induced before term if blood sugar becomes poorly controlled or if there is a complication for the baby. This remains the exception: the preterm birth rate measured by the ENP is stable at 7.0 %, all causes combined, as explained in our article on premature birth in France.
Follow-up for the mother after birth
Blood sugar returns to normal after delivery and insulin is stopped. But the Assurance Maladie stresses the long term. The risk of developing type 2 diabetes is seven times higher and persists for at least 25 years. Cardiovascular risk is 1.7 times higher and the risk of metabolic syndrome two to five times higher. A blood glucose check is scheduled at the postnatal visit, between six and eight weeks, then at three months, before any new pregnancy, and then every one to three years. The risk of recurrence in a subsequent pregnancy is estimated at between 30 and 84 %.
Breastfeeding is not contraindicated. The official data on breastfeeding in France highlight its benefits for both mother and child, and the Assurance Maladie pages on gestational diabetes set no restrictions.
Key takeaways
Gestational diabetes affects one pregnancy in six in France, a proportion that rose by half between 2016 and 2021. Screening is based on risk factors, with a fasting blood glucose test followed by an OGTT between 24 and 28 weeks. When well controlled, it does not prevent a normal delivery or a healthy baby, although the newborn's blood sugar needs to be monitored in the first few days. For the mother, it is above all a long-term warning sign, which calls for regular follow-up long after the birth.
Sources
- Inserm, Santé publique France, DREES, “Enquête nationale périnatale: résultats de l'édition 2021”, press release and report, 6 October 2022.
- Assurance Maladie (ameli.fr), “Diabète gestationnel” section: definition and risk factors, screening, treatment and follow-up, delivery and postnatal follow-up, pages updated on 31 January 2025.
- Collège national des gynécologues et obstétriciens français and Société francophone du diabète, clinical practice guidelines “Le diabète gestationnel”, 2010.
