In recent decades, China has witnessed rapid lifestyle and socioeconomic changes characterized by changes in dietary intake and decreased physical activity [15]. The report released in China shows that 148.2 million people, comprising 72.1 million female patients, have prediabetes. Among women between the ages of 20 and 39 years, approximately 5.6 million have DM (3.2%) and 15 million have prediabetes (9%) [16]. Prediabetes is defined as impaired glucose tolerance and/or abnormal fasting glucose levels.
The dramatic increase in GDM can be attributed to parity and age. In our study, the average maternal age in the GDM group was 29.6 years, which was markedly higher than that in the control NP group. The percentage of multiparas in the GDM group was 40.3%, which was obviously higher than that in the control group. Moreover, patients of advanced maternal age were prone to GDM, and the GDM group has a higher percentage of multiparas.
Regarding the specific eating habits of Chinese people and the lack of sufficient exercise during pregnancy, obesity in the GDM group (37.9%) was 3.27-fold that in the NP group (11.6%) (Table 1). A previous study revealed that normal weight accounted for most NPs [17]. In this study, however, 56% and 49.3% of the patients in the NP and GDM groups, respectively, were overweight.
A higher BMI, AC, and fasting glucose in the first trimester of pregnancy increased GDM risk [18]. Excessive gestational weight gain, according to the targets set by the Institute of Medicine (IOM), was associated with cesarean section, LGA and macrosomia. Modification of the IOM criteria, including more restrictive targets, did not improve perinatal outcomes [19]. Our results confirm that obesity in pregnancy can lead to adverse pregnancy outcomes. There was a high percentage of obesity in the GDM group, and the rate of macrosomia in the GDM group was 1.96-fold that of the control group.
In a previous study, the incidence of fetal macrosomia (the main outcome) was significantly higher in the GDM group (20.0%) than in the control group (3.6%) [20]. In our research, fetal macrosomia was observed in 9.7% of women in the control group and 19.1% of women with GDM.
SFH and AC are used in obstetrical departments and are two routine measurements. They have clinical significance for predicting infant size and as a reflection of the pregnant woman’s nutritional status for reference. The SFH chart shows high performance in predicting both SGA and LGA newborns of DM-2, GDM and MGH mothers. These findings support the internal validation of the SFH chart, which may be implemented in the prenatal care of patients with diabetes and pregnancy [12]. The SFH measurement is primarily practiced to detect fetal intrauterine growth restriction (IUGR). Undiagnosed IUGR may lead to fetal death, as well as increased perinatal mortality and morbidity [21].
To our knowledge, this is the first time that the notion of combining SFH and AC to calculate the ISFHAC was put forth as a new indicator of pregnancy outcome.
Regarding the AUCs of different parameters, the AOC for the ISFHAC is the largest among the NP and GDM groups. Thus, we think that the relationship between the ISFHAC and macrosomia is relevant. In this study, the cutoff points for the ISFHAC are 37 and 41.7 in the control and GDM groups, respectively; women in the high bin of the index were prone to adverse pregnancy outcomes. Interestingly, 41.7 was the lower bound of the ISFHAC, which is in accordance with obesity in GDM, and 37 was the lower bound of the ISFHAC in the control group, which is also in accordance with obesity.
We were interested in the high index group. Here, the high ISFHAC predicted (75.9%) most of the macrosomia cases in the GDM group, and this rate was higher than that of the obesity-based grouping (60.1%).
In the NP group, the high ISFHAC predict 81.3% of macrosomia cases, and obesity predicted 25% of macrosomia. The high ISFHAC prediction ability for macrosomia was better than that of the obesity-based grouping.
In another validation dataset, the high ISFHAC predicted most of the macrosomia cases in the NP and GDM groups. High ISFHAC was a risk factor for macrosomia.
All measures used should aim to prevent excessive SFH and AC, and the high ISFHAC group needs exercise or dietary intervention. Chinese GDM prevention and treatment programs should target overweight and obese adults with central obesity. Interpregnancy SFH and AC control is an important target to reduce the risk of an adverse perinatal outcome in a subsequent pregnancy.
Further studies are needed to determine whether the ISFHAC can predict fetal weight in different GA groups. We hope to provide the ISFHAC chart using the index at different GAs to predict fetal weight.