In this study most women with obesity attained an adequate gestational weight gain through a dietary and physical activity intervention. We found a strong association between adequate gestational weight gain and a lower risk of gestational hypertension and preeclampsia in women with obesity class I, and a lower rate of large for gestational age birthweight in women with obesity class II. In addition, a non-statistically significant lower rate of gestational diabetes was detected in women with obesity class II, and an overall low rate of gestational diabetes was diagnosed in the entire cohort.
One limitation was that the questionaries were returned by 59% of women. This percentage limits the considerations about the adherence to quality of diet and physical activity in both groups. There was an improvement of the PREDIMED score in both groups. This probably reflects the effect of the educative information that both arms received. Another remark is that the adherence to the proportion and quantity of nutrients was not evaluated. Physical activity was not increased substantially. To change the possibilities of physical activity during pregnancy in women with obesity is a challenge for clinicians and educators. Patients and clinicians should be informed about safety and benefits of exercise during pregnancy that include lower diagnosis of gestational diabetes, higher vaginal deliveries, and no differences in preterm or low birthweight (24, 30).
Women with pre-pregnancy obesity are at a significant risk of excess weight gain and obesity during midlife. Many women with obesity attribute their adult weight gain to pregnancy. Conversely, an adequate gestational weight gain is correlated to the ability to control weight after pregnancy (2). Overweight or obesity affects an increasing number of women of childbearing age. Weight retention after delivery is an important cause of excess weight. Indeed, half of women gain more weight than appropriate during pregnancy, according to a meta-analysis of more than 5 000 women worldwide (6). Women with obesity gain a total weight that is lower than in normal weight women (1, 24). However, in the case of women who have overweight or obesity, this percentage of excessive weight gain increases to 60% during pregnancy (1, 24). Excessive gestational weight gain is associated with more weight retention after pregnancy and obesity later in life, further amplifying the problem of obesity.
Several studies reflect an association between a high pre-pregnancy BMI and excessive gestational weight gain and maternal risks during pregnancy and adverse birth outcomes (4, 6). Maternal risks include gestational hypertension, preeclampsia, gestational diabetes and caesarean births (1), and neonates are more likely to be large for gestational age (5, 7, 8). This excessive fetal growth can lead to cesarean section, trauma of the birth canal, shoulder dystocia, asphyxia and these children are at risk of overweight or obesity later in life (6–8, 31). Gestational diabetes is diagnosed in 35% of women with obesity (32). Contrarily, we observed gestational diabetes in only 8.3% of this cohort of women that received information about diet and physical activity with a goal of an adequate gestational weight gain. This rate was lower in women of the intervention group. The difference between the groups cannot be statistically significant due to the small numbers involved. A low rate of gestational diabetes is plausible since a healthy diet and physical activity during pregnancy improve glycemia and insulin sensitivity. Previous studies have found that physical activity promotes the glucose uptake of skeletal muscle and increases mitochondrial density and the expression of glucose transporter proteins. In addition, oxidative stress is reduced (33).
Some studies relate a low gestational weight gain with small for gestational age birthweight, but this association is influenced by factors such as maternal pre-pregnancy BMI (24). The objective of a gestational weight gain of 5–9 kg was compatible with a caloric intake recommendation of 24–30 kcal/kg/d in the intervention group. This moderate restriction to 24 kcal/kg/d is not related to an enhanced production of ketone bodies or a restricted fetal growth in women with obesity (34). In this sense, a gestational weight gain of 5 kg in women with obesity class II and gestational diabetes was not related to SGA birthweight in a previous study (35). However, gestational diabetes is a factor related to fetal overgrowth and the rate of SGA newborns could be higher in women without diabetes. Gestational diabetes was infrequent in this study, and we did not observe an increased rate of SGA birthweight in this cohort of women with obesity, nor in analysis by subgroups by obesity class. However, excessive gestational weight gain has been associated with a 78% increase of stillbirth and neonatal deaths due to vascular and metabolic disturbances that cause placental dysfunction, congenital anomalies, and infections in women with obesity. Causes of placental vascular malperfusion include dyslipidemia, insulin resistance, hyperglycemia, low-grade inflammation, endothelial dysfunction, and oxidative stress (36). This malperfusion could also contribute to the rates of small for gestational age birthweights in women with obesity.
A Cochrane review of dietary and physical activity interventions to regulate gestational weight gain resulted in a 20% reduction of excessive gain while only minimally increasing the risk of a low weight gain. However, this benefit was attenuated in women who had overweight or obesity (23). Unfortunately, most health behavior interventions designed specifically for women with obesity, such as the Limit, ROLO or the Fit for Delivery Study, have failed to demonstrate a significant effect on gestational weight gain (11–20, 24). Two exceptions include the LiP (Lifestyle in Pregnancy) (21) and the TOP (22) randomized trials. The LIP trial included dietary counselling, inscription to a fitness center and personal coaching. Women with obesity gained less weight (7.0 vs 8.6 kg) but differences in excessive gestational weight gain were not statistically significant, maybe influenced by the fact of a lower than recommended weight gain in both arms. The TOP study found that women assigned to a physical education program decreased weight gain by 1.38 kg and women had an adequate gestational weight gain more frequently (50–55% in the intervention vs 37% in the control group). It is possible that the lifestyle program needs to be more intense and require an earlier start in women with obesity. The motivational interviews and recruitment during the first weeks of pregnancy may have been the key to the success of the PREDG program.
In conclusion, to moderate gestational weight gain benefit women with obesity in terms of lower rates of gestational hypertension or preeclampsia and large for gestational age neonates. We encourage clinicians and patients to address gestational weight gain as a modifiable risk factor for several adverse maternal and neonatal outcomes.