30th May 2021, Dr Chee L Khoo
Obesity and GDM are the most common clinical risks in obstetric practice increasing the probability of a variety of pregnancy related complications compared to women with a normal BMI and normal glucose tolerance. These complications include pregnancy induced hypertension (PIH), emergency caesarean sections (EMCS), pre-eclampsia (PE), post-partum haemorrhage (PPH), large-for-gestational age infants (LGA) and macrosomia. For women who are obese, it is recommended that they gain between 5-9 kg (1). Of course, excessive maternal weight gain not only increases the risk of developing gestational diabetes mellitus (GDM) and macrosomia, it can affect the future health of the offspring especially in women who already have a high BMI. What about inadequate gestational weight gain (GWG) or even weight loss during pregnancy? Is it good or bad?
The results of less than recommended weight gain during pregnancy is conflicting. Women with GDM, minimal weight gain, well below guideline recommendations, had a trend to higher rates of small for gestational age infants (SGA) which has its own long term sequelae to the offspring . On the other hand, overweight and obese GDM Asian women who reported minimal weight gain and tight control of blood glucose levels during pregnancy may eliminate most of the adverse pregnancy outcomes experienced . In a recent review, Kalliala et al.  found that weight loss interventions during pregnancy might lead to reductions in the rates of total caesarean sections, pre-eclampsia, LGA, GDM and prematurity. Moreso, Oken et al.  found that, in obese pregnant women, the lowest predicted prevalence of adverse pregnancy outcomes occurs with weight loss.
Perhaps, a recent retrospective cohort study of pregnancy outcomes for women with GDM and obese recorded in the Atlantic DIP database over a 7-year period might shine further light on the matter (6). The ATLANTIC Diabetes in Pregnancy Group (ATLANTIC DIP) consists of a number of antenatal centres along the Irish Atlantic seaboard and offers pre-pregnancy, antenatal and postnatal care to women with pre-gestational diabetes and GDM. 754 women with a BMI ≥ 30 kg/m2 and GDM were identified. The women were categorised into:
- Group 1: women with weight loss and/or weight gain of <5 kg (n = 237): 91 on diet, 146 on insulin
- Group 2: women with weight gain of 5–9 kg (n = 77): 29 on diet, 48 on insulin and
- Group 3: women with weight gain >9 kg (n = 440): 159 on diet, 281 on insulin
Women are advised to monitor their blood glucose levels 7 times per day (fasting, pre-meals, 1 h post meals, and at bedtime). Blood glucose targets are set at 5.3mmol/L for fasting/pre-meal, and 7.8 mmol/L 1 h post meals. Insulin is commenced when blood glucose readings are outside these ranges on more than 3 successive days. The women were managed in a combined diabetes antenatal clinic and reviewed every 2–4 weeks by a multidisciplinary team that includes an obstetrician, diabetologist, and midwife/diabetes nurse specialist. Each patient receives a consultation on diet changes at GDM diagnosis and additional consultations as required. During this consultation, the patient receives advice about carbohydrate intake and distribution.
Despite this being a retrospective study, age/years, ethnicity, family history of diabetes, smoking status, baseline BMI), booking SBP and booking DBP, gestational week of GDM diagnosis and first recorded HbA1C were not statistically significant between groups. The women were treated either with medical nutritional therapy (GDM-D) only or diet and insulin (GDM-I).
- In the GDM-D subgroup, booking SBP and DBP were significantly higher in women with weight gain of <5 kg compared to those with ideal weight gain.
- Overall, women with weight gain <5 kg were more likely to have PPH or polyhydramnios compared to women with ideal weight gain. Rates of antepartum haemorrhage, PE, PIH and caesarean section were not significantly different between groups.
- In the GDM-I group, women with weight gain of <5 kg had higher rates of PPH approaching but not reaching statistical significance. All other outcomes were similar.
- In the GDM-D group, women with weight gain of <5 kg were more likely to have PPH and PIH compared to the ideal weight gain group.
- In logistic regression analysis, women with weight loss or weight gain of <5 kg had higher odds ratios to develop PIH and polyhydramnios but when adjusted for smoking status, family history, ethnicity and age, the association is lost.
- There was no statistical difference in rates of prematurity, macrosomia, RDS, hypoglycaemia, congenital malformations, shoulder dystocia, NICU admissions for weight gain <5 kg compared to ideal weight gain groups respectively.
- Interestingly, the rate of LGA was higher in those with a weight gain of <5 kg compared to those who gained an ideal weight.
What do all these outcomes mean?
Overall, this study showed that weight gain less than recommended guidelines appears safe and is not associated with any further increase in adverse outcomes. There was an increase in rates of prematurity in women who did not gain adequate weight. The risk of SGA was not higher in women who lost weight or did not gain adequate weight. This is in contrast with the study by Park et al (2011) which showed that weight loss in obese pregnant women diagnosed with GDM is associated with higher odds for SGA and preterm delivery <34 weeks (3). However, that study did not used the IADPSG criteria for the diagnosis of GDM.
The study by Katon et al (2013) also did not find that weight loss in women with GDM was associated with an increase risk of SGA (7). Other studies supporting the lack of association between weight loss and SGA include Baur et al (8) and Kurtzhal et al (9). Perhaps, women with GDM received more information on the diet component of the treatment, and while reducing the calorie intake, the density of the nutrients is maintained or increased thus preventing SGA.
In this study, there was a suggestion of LGA in women who did not gain the recommended weight during pregnancy although the increase in LGA was lost when confounders were considered. Perhaps, women in this cohort the pre-pregnancy BMI might have an impact on foetal growth not compensated by weight loss or minimal weight gain during pregnancy.
Thus, obese women who has GDM who do not gain the “usual” weight during pregnancy should not necessarily cause alarm. There may be an increase in LGA but that may be more related to the obesity than gestational weight gain (or the lack of).
- Medicine. Io. National Academy of Sciences, subcommittee on nutritional status and weight gain during pregnancy. Washington, DC, USA: National Academy Press; 1990. pp. 1–233.
- Chung JG, Taylor RS, Thompson JM, Anderson NH, Dekker GA,
- Park JE, Park S, Daily JW, Kim SH. Low gestational weight gain improves infant and maternal pregnancy outcomes in overweight and obese Korean women with gestational diabetes mellitus. Gynecol Endocrinol. 2011;27:775–81.
- Kalliala I, Markozannes G, Gunter MJ, Paraskevaidis E, Gabra H, Mitra A, et al. Obesity and gynaecological and obstetric conditions: umbrella review of the literature. BMJ. 2017;359:j4511.
- Oken E, Kleinman KP, Belfort MB, Hammitt JK, Gillman MW. Associations of gestational weight gain with short- and longer term maternal and child health outcomes. Am J Epidemiol. 2009;170:173–80.
- Bogdanet D, Mustafa M, Khattak A, Shea PMO, Dunne FP. Atlantic DIP: is weight gain less than that recommended by IOM safe in obese women with gestational diabetes mellitus? Int J Obes (Lond). 2021 May;45(5):1044-1051. doi: 10.1038/s41366-021-00769-7. Epub 2021 Feb 24. PMID: 33627772.
- Katon J, Reiber G, Williams MA, Yanez D, Miller E. Weight loss after diagnosis with gestational diabetes and birth weight among overweight and obese women. Matern Child Health J. 2013;17:374–83.
- McGowan JE. Neonatal hypoglycemia. Pediatrics in Review. 1999;20:e6–e15.
- Kurtzhals LL, Nørgaard SK, Secher AL, Nichum VL, Ronneby H, Tabor A, et al. The impact of restricted gestational weight gain by dietary intervention on fetal growth in women with gestational diabetes mellitus. Diabetologia. 2018;61:2528–38.