ABSTRACT
Introduction Diabetes mellitus has been identified as a risk factor for a severe course of COVID-19 in pregnant women. In addition, it has been suggested that SARS-CoV-2 infection may trigger the development of diabetes mellitus through direct destruction of the pancreatic Langerhans cells. Until now, little data regarding an association between gestational diabetes (GDM) and risk of SARS-CoV-2 infection during pregnancy is available. The aim of our study was to investigate this possible association in our population using a case-control model. Material and methods We included 85 pregnant women with symptomatic or asymptomatic SARS-CoV-2 infection in our study, who were managed at our institution starting with May 2020 to date. We matched these cases 1:2 with a cohort of women managed at our hospital between before 30.10.2019 based on parity, BMI and ethnicity. Screening for gestational diabetes by a 75 mg oral glucose tolerance test (OGTT) was performed at 26 weeks' gestation in all women. Clinical data on pregnancy outcomes were collected. Results Of the 85 women included in the case group, OGTT was available in 75 cases. Diagnosis of gestational diabetes was made in 23 women in the case group (30.66%), vs. 20 in the control group (13.42%). This difference was statistically highly significant (p 0.0036 through two-sided Fisher's exact test, where p<0.05 was considered as significant) . Mean age was 30.42 years old (SD±4.65) in the case group and 30.39 years old (SD±4.77) in the cohort group. Mean BMI was 26.10 (SD±5.13) in the case and 25.67 in the control group (SD±5.10) When classifying patients into not-overweight (BMI<25 kg/m2) vs. overweight (BMI≥25 kg/m2), 60.86% of the women with GDM in the case group were overweight vs. 80% in the control group. This difference was statistically significant. According to the WHO classification of the severity of COVID19, most women presented with mild or moderate course of the disease. In four women, hospitalization was necessary because of severe COVID-19 infection. Of these, two (50%) suffered from GDM. Discussion The main finding in our study is a significantly higher rate of GDM among women with SARS-CoV-2 infection during pregnancy, when compared to a control group. We speculate that GDM increases the risk of SARS-CoV-2 infection in pregnant women. On the other hand, the infection might increase the risk of developing GDM. Interestingly, in the women who developed GDM in the control group, significantly more patients with overweight were found than in the case group (80 vs. 60.86%). It remains open, if SARS-CoV-2 acted as an additional 'promoter' for developing GDM in these women. To our knowledge, this is the first study showing a possible correlation between GDM and SARS-CoV-2 infection. Further studies are needed to confirm this association and the potential mechanism behind it.
ABSTRACT
Introduction A higher risk for adverse pregnancy outcome has been described in association with SARS-CoV-2 infection, which partially could be explained through alteration of the placental function. However, no significant placental damage in SARS-CoV-2-positive women could be found to date, as no histopathological 'footprint' in association with SARS-CoV-2 is yet available. Birthweight/placental weight ratio (b/p ratio), also defined as gram fetus per gram placenta, is a marker of placental efficiency. A high b/p ratio seems to be associated with adverse obstetrical outcome, revealing an increased nutrient transfer to the fetus, who despite its normal weight, seems to be at risk by 'outgrowing' its placenta. Given the inconsistency of data regarding placental histopathology, we decided for evaluation of the placental weight after SARS-CoV2 infection during pregnancy, by performing a case-control analysis. Methods We included in our study data originating from 153 women who suffered from SARS-CoV-2 infection during pregnancy and delivered since May 2020 at three large obstetrical centres in Switzerland. Placental weight was assessed in a standard manner. Placental weight and b/p ratio were compared to published reference charts (Thompson et al, BJOG 2007). Crude odds ratio (OR) was estimated using simple logistic regression depending on pregnancy trimester at diagnosis of SARS-CoV-2 infection. Results Placental weight was inferior or equal to the 10th centile in 42% (65/153) and inferior or equal to 3rd centile in 19% (29/153) of the cases. The risk of placental low weight was not significantly different between each trimester of infection. Multiparty was the only significant associated factor to the risk of low placental weight. Incidence of fetal growth restriction (FGR) was 11.6% (18/153), whereas presence of preeclampsia was noted in 0.03% of the cases (5/153). Gestational diabetes was present in 19.60% of the cases (30/153). B/p ratio was>50th centile in 80.4% of the cases and>90th centile in 31.37% of the cases. Discussions In our study, the absolute rate of low placentas weight was critically increased, leading to an elevated the b/p ratio, which raises concerns about the stability of the placental/fetal unity in these cases. The upregulated nutrient transfer capacity could be a sign that presumably low-risk fetuses are actually at high risk, and that SARS-CoV-2 could act as a 'promoter' for the destabilisation of the placental-fetal dyad in these pregnancies. Moreover, given the unexplained elevated GDM rate in our population, it remains open if this as well could be partially explained through an 'upregulation' attempt of the placenta, in order to provide more energy to the fetus at risk. This could be particularly relevant for the yet controversial issue of increased stillbirth rate in SARS-CoV-2 infection during pregnancy. In this regard, intensified fetal surveillance could be a reasonable option in these cases.