Intrapartum Glycemic Control and Clinical Outcomes

Abstract

Current recommendations encourage strict intrapartum glycemic control for individuals with diabetes in pregnancy to optimize maternal and neonatal outcomes. However, established evidence is limited in providing a strong association between strict maternal blood glucose control and neonatal outcomes.

Management Guidelines, Monitoring, and Fluid/Insulin Systems

The prevalence of diabetes is increasing among women of reproductive age, which may be attributed to simultaneous increases in obesity and advanced maternal age (1). It is estimated that ∼7% of pregnancies are affected by any type of diabetes, including gestational diabetes mellitus (GDM) (2). Adverse outcomes associated with diabetes in pregnancy are typically related to the degree of maternal hyperglycemia at conception and during pregnancy. Neonatal hypoglycemia is one of the most common neonatal adverse outcomes for pregnancies complicated by diabetes, affecting nearly 50% of these gestations (3). Pregnancy interventions are strongly recommended and widely researched to reduce maternal and neonatal complications related to diabetes. At this time, intrapartum interventions include close monitoring of labor and treatment of maternal hyperglycemia.

Current guidelines recommend insulin to maintain strict intrapartum glycemic control to reduce neonatal hypoglycemia (4–7). Although blood glucose is monitored closely in people with diabetes during labor, the role of strict glycemic control is uncertain with regard to maternal and fetal outcomes, and particularly neonatal hypoglycemia (8–10). The currently endorsed practice is based primarily on observational studies (11–17). Furthermore, the primary neonatal outcome emphasized by actively and strictly managing intrapartum glycemic control is neonatal hypoglycemia, which is controversial with regard to its definition, treatment thresholds, clinically significant values, and appropriate timing of screening (18).

Physiology of Maternal Blood Glucose During Labor

Maternal blood glucose values in labor can be influenced by several maternal factors, including BMI, diabetes type, antenatal glycemic control, insulin and fluid system management, and the metabolic demands of labor. These metabolic demands may increase the risk of maternal hypoglycemia during labor because of increased glucose utilization (19). An increase in stress hormones and increased metabolic stress because of labor, while oral intake usually decreases, have led to many intrapartum protocols, including glucose infusion as part of fluid management. In a prospective study of 112 individuals using continuous glucose monitoring (CGM) and point-of-care (POC) blood glucose testing during labor, we found a median POC glucose level of 100 mg/dL and a mean CGM sensor glucose of 102.6 mg/dL (interquartile range 89.9–113.5 mg/dL), with 10% of participants requiring an insulin drip in labor because of blood glucose values ≥110 mg/dL (20).

Current Standard Practice Goals

Current recommendations for management of diabetes during labor are to control blood glucose with short-acting insulin subcutaneously or via an insulin drip to maintain hourly glucose readings below a certain threshold. There is mild variation in the recommended maternal intrapartum glucose goal, with the American College of Obstetricians and Gynecologists (ACOG) recommending <110 mg/dL and Diabetes Canada, the National Institute for Health and Care Excellence, and the Australian Diabetes in Pregnancy Society recommending 72–126 mg/dL (4,5,7).

Glucose Monitoring

The recommended timeline of monitoring blood glucose ranges from “close monitoring” (7) to hourly readings (4,5), affecting resource utilization from direct costs (e.g., testing supplies, laboratory fees, and medications) and indirect costs (e.g., nursing efforts and patient satisfaction). The mode of monitoring blood glucose for many patients with diabetes remains POC fingerstick testing with a bedside glucose meter. However, there is a gradual transition to using CGM in pregnancy for individuals with pregestational diabetes. As more patients elect for CGM use in pregnancy, more will likely elect for intrapartum CGM use as well. Most studies evaluating CGM and its outcomes during labor are specific to individuals with type 1 diabetes (21–23).

Fluid Management

Fluid management is closely related to the physiology of labor, as discussed previously, and the type of insulin management system used to treat hyperglycemia in labor. Because of increased metabolic demands and glucose utilization during labor, many intrapartum protocols recommend the use of dextrose or glucose infusion throughout all or certain phases of labor (4). For patients who become hypoglycemic, i.v. dextrose is recommended, along with oral supplementation. A randomized controlled trial (RCT) by Rosenberg et al. (24) compared two forms of fluid and insulin management for laboring individuals with type 2 diabetes or GDM. Patients received either 5% dextrose in normal saline with a continuous insulin drip (goal blood glucose 81–100 mg/dL) or rotating fluids, with 5% dextrose in lactated ringers given if maternal blood glucose was <100 mg/dL or 100–140 mg/dL and via insulin drip if blood glucose was >140 mg/dL. There were no between-group differences in the rate of insulin drip utilization, mean maternal blood glucose, or neonatal outcomes.

Insulin Management

Management strategies involving insulin to avoid maternal hyperglycemia vary, often depending on the type of diabetes and maternal glycemia status. ACOG recommends using regular insulin via i.v. infusion if blood glucose values are above their recommended threshold (25,26). People with type 1 diabetes using an insulin pump may often continue their basal rate of insulin infusion during labor. A study by Wilkie et al. (27) compared the use of continuous subcutaneous insulin infusion versus i.v. insulin infusion in intrapartum care in people with type 1 diabetes and found no difference in initial neonatal blood glucose, suggesting the equal utility of either method. A retrospective cohort study of 161 people with type 1 diabetes also compared outcomes related to insulin management strategies. Labor glucose values were compared in people who used an insulin pump during pregnancy and continued it in labor, those who used an insulin pump during pregnancy and switched to i.v. insulin in labor, and those who used insulin injections in pregnancy and switched to i.v. insulin during labor (28). This study, by Drever et al. (28), identified no significant differences between intrapartum maternal mean or median glucose values and rates of hypoglycemia among the three groups. However, lower maternal blood glucose in the pump/pump group was seen when compared with the pump/i.v. group (median glucose 102 vs. 115 mg/dL, P = 0.02), indicating better and more efficient glycemic control in the pump/pump group.

Clinical Implications: Neonatal Hypoglycemia

Neonatal hypoglycemia, of varying definitions (8), is the most common complication in neonates born to mothers with diabetes. The rate of hypoglycemia is ∼40–50%, and hypoglycemia requiring i.v. treatment ranges between 5 and 7% (3). Hypoglycemia is associated with an increased risk of neonatal intensive care unit (NICU) admission, given its short-term effects on the neonate, including irritability, seizures, and brain damage, and long-term effects, including neurodevelopment deficit (29–32). Although intrapartum hyperglycemia is seen as an ultimate risk factor for neonatal hypoglycemia, neonatal hypoglycemia is also linked to pre-pregnancy risks such as BMI, as well as pregnancy-related factors, such as glucose control during pregnancy, antenatal corticosteroid administration, and neonatal weight at delivery (33–38).

Not only does the definition of neonatal hypoglycemia vary (e.g., initial blood glucose <45 vs. 25 mg/dL, glucose requiring i.v. therapy, and others), but data on the appropriate time to screen for hypoglycemia are limited, with screening strategies suggesting that hypoglycemia can occur as early as 30 minutes after delivery as well as >24 hours after delivery, as acknowledged by the American Academy of Pediatrics (38). Despite the lack of an exact agreed-upon value for hypoglycemia in neonates, it is suspected that neonatal glucose levels fall 1–2 hours after birth, with at-risk neonates, such as those born to mothers with diabetes, at even further risk 24 hours post-delivery (38). Generally, however, at-risk neonates are screened for hypoglycemic symptoms universally within the first 24 hours after delivery.

The History of Intrapartum Glycemic Care

After several studies as early as the 1950s (39) suggested a correlation between maternal hyperglycemia late in pregnancy and labor and average neonatal blood glucose, Light et al. (40) proposed an inverse relationship between maternal hyperglycemia and neonatal hypoglycemia. This relationship is synergistic with the biological reasoning that, in the presence of maternal hyperglycemia in pregnancy, fetuses are exposed to hyperglycemia and have consequential fetal pancreatic hyperplasia and hyperinsulinemia (41). Strict glucose control in labor was then first introduced after a glucose-controlled insulin infusion system was used in a few patients at term in the late 1970s, informing our present-day aforementioned management strategies (13,16). Labor insulin regimens were then explored to optimize insulin delivery, but did not necessarily focus on whether control of maternal hyperglycemia improved neonatal outcomes (11,15). The current insulin dextrose protocol used on most labor wards was first published by Lean et al. (11) >30 years ago, in a study in which insulin was initiated in 25 insulin-treated patients with diabetes if their blood glucose was >126 mg/dL. As discussed previously, a study evaluating rotating fluids versus an insulin drip arm in 36 individuals found no difference in maternal blood glucose or neonatal hypoglycemia (24). Interestingly, further studies have shown that implementation of an insulin protocol in labor was associated with increased rates of neonatal hypoglycemia, as found by Dude et al. (42) after implementation of an insulin drip protocol among parturient patients with diabetes.

Studies Evaluating Intrapartum Glycemic Care and Its Clinical Implications

Current published trials of intrapartum glycemic management are described in Table 1, with recognized limitations of retrospective designs, small sample sizes, and lack of agreement on definitions of significant adverse outcomes (e.g., neonatal hypoglycemia) (9,43–48). Literature regarding strict glycemic control during labor is inconsistent, with some studies finding an inverse relationship between maternal hypoglycemia and neonatal blood glucose and others finding a lack of association or even an increased risk of adverse neonatal outcomes with tight maternal glycemic control (9,10,42,49). Despite these conflicting findings, strict glycemic control is still advised.

Table 1.

U.S. Studies of Intrapartum Glycemic Care

Article	Population(s)	Study Description	Findings
Roman et al. (47)	GDM (n = 80) and diabetes (n = 72)	Retrospective cohort study; evaluated optimal glycemic control (glucose 60–100 mg/dL)	Optimal control within 6 hours of delivery reduced neonatal hypoglycemia.
Zelivianskaia et al. (46)	GDM and diabetes (n = 191)	Retrospective cohort study; risk factors for neonatal hypoglycemia	Good intrapartum glycemic control (“controlled the entire time”) did not affect neonatal hypoglycemia.
Hamel et al. (9)	GDM (n = 74)	RCT; tight glycemic control (<100 mg/dL) with hourly glucose meter checks vs. liberal control (<120 mg/dL) with glucose meter checks every 4 hours	First neonatal mean blood glucose level was similar between groups, and mean neonatal blood glucose level at 24 hours was lower in the group with tight control.
Fleischman et al. (45)	GDM (n = 235) and diabetes (n = 99)	Retrospective cohort study; tight (<110 mg/dL) vs. less tight (110–139 mg/dL) vs. liberal (≥140 mg/dL) intrapartum glucose control	There was no difference in the primary outcome of neonatal hypoglycemia within 2 hours of birth.
Anwer et al. (43)	GDM (n = 679) and diabetes (n = 174)	Retrospective cohort study; evaluated neonatal hypoglycemia	Those with normal glucose (<110 mg/dL) and elevated glucose levels intrapartum (>110 mg/dL) did not have different outcomes in neonatal hypoglycemia.
Alrais et al. (44)	Type 2 diabetes (n = 215)	Retrospective cohort study; evaluated mode of delivery and insulin infusion	There was no difference in neonatal hypoglycemia in those with planned cesarean delivery and those with vaginal delivery attempt. There was also no difference in neonatal hypoglycemia in those attempting vaginal delivery who required insulin vs. those who did not require insulin.
Bitar et al. (48)	GDM (n = 61) and diabetes (n = 35)	Equivalence RCT; evaluated usual care (110 mg/dL) with permissive intrapartum care (<180 mg/dL) in labor after 34 weeks’ gestation	There was no difference in first neonatal mean blood glucose within 2 hours of delivery. There was no difference in the secondary composite neonatal outcome. There was a higher risk of insulin drip in the group receiving usual care.

A systematic review by Yamamoto et al. (8) evaluating this relationship of maternal hyperglycemia and neonatal hypoglycemia extensively reviewed 23 cohort studies, of which 17 did not find a significant relationship and others did not adjust for known confounders (e.g., gestational age). Only two of these retrospective studies evaluated in-target versus out-of-target glycemic control and found contradictory results (28,50).

Multiple retrospective studies evaluating prediabetes and GDM in labor suggest that controlled glucose levels intrapartum do not improve neonatal hypoglycemia rates (43,46). Other studies have demonstrated no difference in rates of hypoglycemia with or without insulin drip during labor (12,44), highlighting the likelihood of preexisting fetal hyperinsulinism from pancreatic hyperplasia, possibly from longstanding maternal hyperglycemia antepartum (41). Another retrospective cohort study comparing tight (<110 mg/dL), less tight (110–139 mg/dL), and liberal (≥140 mg/dL) intrapartum glucose control emphasized the lack of a relationship between degree of control and neonatal hypoglycemia (45). A multicenter prospective study evaluating the relationship between intrapartum CGM and neonatal hypoglycemia in individuals with either prediabetes or GDM sought to establish the feasibility of CGM in labor (20). In 112 individuals who met the study’s inclusion criteria, the average time in range (70–110 mg/dL) was 62%. Both CGM and POC blood glucose monitoring mean glucose values were poor predictors of neonatal hypoglycemia; however, time above range (TAR; >110 mg/dL) of ≥61% with CGM was associated with a higher rate of neonatal hypoglycemia than TAR <61% (45.8 vs. 25.9%, P = 0.06) (Figure 1).

Figure 1.

Medians and interquartile ranges of maternal blood glucose levels by hour before delivery of neonates with hypoglycemia (red) and without hypoglycemia (black line). Reprinted with permission from ref. 20.

Based on a PubMed Central search in March 2025 using search terms “intrapartum glucose” and “intrapartum neonatal hypoglycemia,” only two RCTs were identified evaluating glucose control intrapartum (9,48).

Hamel et al. (9) randomized 76 patients with GDM to tight control (glucose measurements hourly with a goal of 70–100 mg/dL) versus liberalized control (glucose measurements every 4 hours with a goal of 70–120 mg/dL). This single-center trial found no difference in the primary outcome of initial neonatal glucose level taken within the first 2 hours of life. Furthermore, tight control was associated with lower mean blood glucose levels in newborns’ first 24 hours of life. As expected, those in the tight control group were more likely than those in the liberal group to receive insulin during labor (32 vs. 3%, P = 0.01).

Our group attempted to compare the equivalence of standard of care (considered to be strict intrapartum glycemic control with a maternal blood glucose goal of 70–110 mg/dL) with permissive intrapartum care (allowing maternal intrapartum glycemic goals to be between 70 and 180 mg/dL) (48). The equivalence RCT included 96 participants with any kind of diabetes at ≥34 weeks’ gestation, the majority of whom (96%) had type 2 diabetes or GDM. Participants were randomized in a 1:1 manner to either strict or permissive intrapartum care. The primary outcome was average first neonatal blood glucose level measured via heel stick within 2 hours of birth. An adjusted mean difference (aMD) was used to quantify the primary outcome. If the aMD and its 95% CI fell between a margin of equivalence (−10 to 10 mg/dL), the care between groups was considered to be equivalent. We found equivalence in the primary outcome of first neonatal blood glucose between usual and permissive care (57.9 vs. 57.1 mg/dL, aMD −0.72, 95% CI −8.87 to 7.43) (Figure 2). The most common morbidities in the neonatal composite outcome were NICU admission and hypoglycemia, which were similar between groups. Regarding maternal outcomes, usual or strict care was associated with a greater likelihood of having an insulin drip during labor, with eight participants (17%) requiring an insulin drip compared with none in the permissive-care group. Other maternal outcomes were similar between groups.

Figure 2.

Primary outcome reflecting aMD in first neonatal blood glucose. The aMD and 95% CI of the primary outcome fell within the margin, demonstrating equivalence between usual care and permissive care. Reprinted with permission from ref. 48.

Although the current RCTs are limited by sample size and heterogeneity of participants, they support the concept that we have little information to guide our current strategies of intrapartum glucose management, with the optimum maternal blood glucose range unknown.

Maternal Implications Based on Clinical Care

In the studies by Rosenberg et al. (24) and Bitar et al. (48), the rate of insulin drip utilization was higher in those who were managed with a tighter maternal blood glucose goal, without notable neonatal benefit. The risks associated with maternal insulin therapy, such as hypoglycemia, are not to be ignored, nor are the direct costs (e.g., testing supplies, laboratory fees, and medication) and indirect costs (e.g., nursing efforts and patient satisfaction).

Future Directions and Conclusion

In the age of optimally targeting glycemic control antepartum, careful consideration is required to reevaluate the goals and necessity of intrapartum glycemic care. Emerging evidence suggests that our previous conceptions of tight intrapartum glycemic goals helping to avoid neonatal hypoglycemia may be limited and in need of further evaluation. Future studies should also evaluate the optimal blood glucose testing timeline during labor, the type of fluids that should be used during labor, and the best time to evaluate neonatal blood glucose after birth.