This was a retrospective analysis that aimed to determine the relations between the number of AbV in OGTT and the presence of GDMA2. Our study demonstrated that GDMA2 was more prevalent as the number of AbVs in OGTT increased.
The differences between one or two AbVs was less significant, but beyond two AbVs, the risk of GDMA2 has increased significantly. Conversely, upon conducting pairwise comparisons across all AbVs groups, discernible distinctions emerged among each. It should be noted that the absence of significant differences in the likelihood of GDMA2 between one AbV and two AbVs strengths the approach of considering a single AbV in OGTT as indicative of GDM.
The robustness of our primary outcome is reinforced through logistic regression analysis, conducted to identify potential confounders, which revealed that the most influential factor correlated with GDMA2 is the number of AbVs in OGTT.
Hence, it is empirically valid to assert that the increased prevalence of pathological values correlates positively with the likelihood of diagnosing GDMA2 over GDMA1.
Based on these disparities, which have not been previously described in the literature, it can be inferred that the cohort of women with the elevated number of AbVs in OGTT likely represents a population for whom GDM management with diet alone may pose challenges in achieving glycemic control. Consequently, these women may eventually necessitate pharmacological intervention in pursuit of glycemic balance.
Following this fundamental premise, we attempt to explicate the additional findings arising from our research results: We found that the prevalence of maternal composite outcomes was higher with an increased occurrence of AbVs in OGTT. As mentioned above, poorly controlled gestational diabetes raises the overall risk of maternal complications [7, 9–11]. Therefore, our results align with what is known in the professional obstetric literature and previous studies.
We found that a higher prevalence of AbVs correlates with an increased necessity for labor induction. This observation is consistent with the notion that a greater occurrence of AbVs in OGTT is associated with a higher probability of glycemic imbalance and the presence of GDMA2. In gestational diabetes, labor induction is frequently performed to prevent complications such as stillbirth, excessive fetal growth leading to difficult vaginal delivery, or other complications associated with poorly controlled diabetes, as it is known that the risk of complications increases with poorer glycemic control and later gestational age [17]. Furthermore, if we extrapolate that an increased number of AbVs in OGTT corresponds to a heightened likelihood of GDMA2, and as we demonstrated, there is a higher prevalence of induction of labor, it follows logically that gestational week at birth will decrease as the number of AbVs increase- a finding that was observed in our study.
Concerning neonatal outcomes, we found that as the number of AbVs in OGTT increases, the gestational week at delivery decreases. This may be attributed to the higher frequency of labor inductions observed in groups with more AbVs, indicating that as the prevalence of pathological values rises, there are more cases of GDMA2 and presumably fewer instances of good glycemic balance, leading to increased intervention for delivery induction and earlier gestational weeks at birth.
Another finding emerging from our research results is that women with higher occurrences of AbVs in OGTT had a higher presence of episiotomies performed. Previous studies have found that gestational diabetes is a risk factor for episiotomy during childbirth [18–19]. In some international childbirth management guidelines for women with suspected poor glycemic control or high fetal estimated weight, it is recommended to selectively consider performing an episiotomy to prevent OASIS or shoulder dystocia. Therefore, based on the assumption that more abnormal values in OGTT imply higher risk of GDMA2 and poorer glycemic control, it is clear why there is a higher prevalence of episiotomy during childbirth in cohorts with more AbVs.
Our study reveals that women with a heightened occurrence of AbVs in OGTT are at an increased likelihood of requiring pharmacological intervention for glycemic management. This finding can assist clinicians in interpreting OGTT results, promoting heightened vigilance and awareness of potential risks among women demonstrating a higher number of AbVs in the test. Moreover, it can help educate and motivate individuals to follpw proper dietary practices. However, our findings also indicate no significant differences in mode of delivery, incidence of OASIS, or perineal lacerations of grade 1 or 2 between the studied groups.
The differences found between the groups in the neonatal outcomes were specifically concerning gestational age at delivery and Apgar score and did not encompass the majority of neonatal outcomes. Such results may serve as reassuring tools for patients diagnosed with gestational diabetes, even in instances where the number of AbVs is elevated.
OGTT serves not only as a diagnostic tool for GDM but also enables healthcare practitioners to enhance their awareness of potential adverse outcomes for both the mother and neonate through meticulous analysis of abnormal values.
Although previous studies have examined OGTT results and their correlation with obstetric outcomes, to the best of our knowledge, our study is the first to evaluate the relationship between the numbers of AbVs in OGTT to GDMA1/2 and other maternal and neonatal outcomes, in a large cohort. The study by Mor et al. investigated the relationship between the additive OGTT score and neonatal outcomes, finding that a higher additive OGTT score is associated with an increased risk of GDMA2, greater insulin use, and more maternal and neonatal complications [20]. A systematic review and meta-analysis by Chatzakis et al. explored different phenotypes of GDM based on OGTT, comparing women with pathological fasting glucose values to those with pathological post-load glucose values, and to those with combined pathological values [21].. Another study published on a much smaller cohort addressed the relationship between the number of AbVs in the OGTT and neonatal weight only [22], while another study examined the relationship between a single abnormal value in OGTT and the likelihood of developing type 2 diabetes [23].
These studies underscore the importance of carefully examining OGTT results and their association with adverse obstetric outcome, however, no study has specifically examined the number of AbVs in OGTT and their association with adverse obstetric outcomes.
Additionally, our study benefits from the substantial cohort size and the high quality of gathered data. All participants delivered at our medical facility, guaranteeing thorough documentation of pregnancy progression, labor dynamics, and delivery outcomes for each participant. Other studies that attempted to examine the relationship between the number of AbVs in the OGTT and obstetrics outcomes had a much smaller sample size compared to that presented in our study [22,24].
Nevertheless, our study is not free of limitations, largely attributable to its retrospective design. A notable absence of data concerns the extent of glycemic control for each participant during the pregnancy. It is conceivable that some individuals classified under GDMA1 may not have achieved optimal glycemic balance, and there could be variability in clinical glycemic control within the GDMA2 cohort. Also, the level of glycemic control may influence maternal and especially neonatal outcomes, and the lack of such information could obscure some results, necessitating further investigation. However, given the stringent and comprehensive prenatal monitoring and care provided by obstetricians to the majority of pregnant women in our country, it is reasonable to infer that women who maintained glycemic balance through dietary measures without requiring pharmacological intervention were included in the study. It is important to note that the OGTT was originally developed by O'Sullivan and Mahan in the 1960s to predict the onset of type 2 diabetes after pregnancy, and not specifically to identify perinatal morbidities [25]. Unfortunately, we are unable to follow all the women in our cohort to determine whether they developed type 2 diabetes later in life. However, several publications have shown a correlation between the number of pathological values in the OGTT and the likelihood of developing type 2 diabetes during one's lifetime [26–27].