GDM and GWG have been previously reported to be associated with APOs[24, 25]. Considering the conflicting data regarding the relationship between inadequate GWG and APOs in women with GDM and the limited research on the association of the adequate range of GWG at different stages with APOs in GDM, we conducted a retrospective analysis among 1606 pregnant women with GDM. We showed the association between IOM guidelines for GWG, both in total and in the second and third trimesters of pregnancy, and APOs in women with GDM. In the present study, 33.9% of GDM women presented with a GWG below the IOM guidelines, and 31.2% presented with a GWG above the IOM guidelines. In previous studies, the rates of insufficient GWG (29.6%) and insufficient weight gain (12.5%) were found to be lower than our results[13, 20]. This variation may be due to rigorous lifestyle improvements, including nutritional therapy and exercise, leading to a leaner population in our study.
We then analyzed the associations of APOs with total GWG in women with GDM during pregnancy. Our results found that total GWG above the IOM guidelines increased the risk of LGA, macrosomia, cesarean delivery, HDP, and preeclampsia. Our findings were in agreement with several previous reports[24, 26–28]. Gou et al. showed that excessive GWG increased the OR for LGA and macrosomia[20]. Komem et al. demonstrated that total GWG above the IOM guidelines is related to cesarean delivery and LGA in women with GDM[24]. Furthermore, Cheng et al. performed the largest trial to date to retrospectively analyze data among women with GDM, which showed a remarkable risk for cesarean delivery, macrosomia, and LGA among women with GWG above the IOM guidelines[29]. However, Scifres et al. reported that women with both excessive GWG and insufficient GWG had a higher risk for macrosomia, which may be due to a different grouping method[30]. In addition, Cheng et al. showed that women with GWG above the IOM guidelines had a high risk of preterm birth[29]. Huang et al. found that, in general, pregnant women with both insufficient and excessive GWG had a higher risk for preterm birth[13]. In the present study, we showed that pregnant women with total GWG above the IOM guidelines had a lower risk of preterm birth, while pregnant women with total GWG below the IOM guidelines had an increased relative risk of preterm birth. These findings suggest that reasonable GWG among women with GDM may shorten the incidence of preterm birth. In concordance with other reports, our results also showed that women with total GWG below the IOM guidelines had a decreased relative risk of macrosomia, with an increased relative risk of preterm birth and SGA[16, 20, 21]. In contrast, Gou et al. showed that insufficient GWG did not increase the risk for SGA[20].
Recent studies reported the influence of GWG in the second and third trimesters of pregnancy on the incidence of APOs[31, 32]. For example, Bouvier et al. found that women with GWG above the IOM guidelines had an increased relative risk of HDP, cesarean delivery, macrosomia, LGA, and hypoglycemia in the second and third trimesters of pregnancy[31]. Wu et al. calculated GWG ranges using receiver operating characteristic (ROC) curve analysis (ROC targets) in a retrospective cohort study of women with GDM in Shanghai, China. They showed that ROC targets that provide better GWG guidelines during the second and third trimesters could improve pregnancy outcomes[33]. However, studies on the association of GWG in the second and third trimesters in women with GDM with APOs are limited. Thus, in the present study, we further analyzed the effect of IOM guidelines for GWG in the second and third trimesters of pregnancy on APOs among women with GDM. Our results showed that GWG above the IOM guidelines in the second and third trimesters of pregnant women with GDM was associated with a higher risk of HDP, preeclampsia, macrosomia, and LGA. LGA has been reported to be associated with excessive weight gain in the second trimester of women with GDM in a previous Brazilian cohort study by Drehmer et al., which confirms the results of our study[34]. Drehmer et al. also found that insufficient weight gain was associated with SGA. In another retrospective observational study in India, Kashyap et al. found that pregnant women who had poor rates of weight gain in the second trimester were at an increased risk of SGA[35]. However, in our study, there were no statistically significant differences in the relative risk of SGA in the below or above IOM guidelines group. In addition, we found that women with GWG above the IOM guidelines in the third trimester of pregnancy were associated with a significantly decreased risk of preterm birth. However, our findings showed that women with total GWG below the IOM guidelines were associated with a significantly increased risk of preterm birth, which is in contrast with a previous report[34]. The underlying mechanisms for the link between excessive pregnancy weight gain and preterm delivery remain unclear. The inconsistency may be due to the different study populations and the adjusted confounding variables. Our findings on the relationship between APOs among women with GDM and IOM guidelines for GWG in the second and third trimesters may influence clinical practitioners to pay more attention to the control of GWG.
The study has several strengths. First, this study included a relatively large sample size and we adjusted for confounding factors to ensure reliable assessments. Second, we comprehensively analyzed the associations between IOM guidelines for GWG both in total and in the second and third trimesters of pregnancy with APOs in women with GDM, which has rarely been researched previously.
Our study however had several limitations. First, this study was limited due to the retrospective design. Second, some unmeasured confounders including smoking, diet, physical activity, and other factors were not assessed; therefore, the influence of these factors on APOs could not be explored. Third, since our study did not record weight when GDM was diagnosed, we did not investigate the influence of GWG on APOs specifically after the diagnosis of GDM.
In conclusion, our research suggests that GWG above and below the IOM guidelines, both in total and in the second and third trimesters of pregnancy, is a risk indicator for adverse obstetric outcomes in women with GDM. These findings suggest that it is essential to not only maintain an adequate total GWG during pregnancy, but also in the second and third trimesters among pregnant women with GDM. We hope to encourage physicians to deal with GWG using the IOM guidelines and to trigger intervention when it is required, which should help to reduce APOs. Prospective multicenter clinical investigations will be needed to elucidate the potential role of GWG in APOs among women with GDM.