Objective
We sought to evaluate intrapartum metabolic control in gestational diabetes mellitus (GDM) patients and maternal factors influencing intrapartum glycemic control and neonatal hypoglycemia risk.
Study Design
A prospective observational study included 129 women with GDM admitted for delivery. Data collected included maternal intrapartum capillary blood glucose (CBG) and ketonemia, use of insulin, and neonatal hypoglycemia.
Results
In all, 86% of maternal intrapartum CBG values fell within target range (3.3–7.2 mmol/L) without need for insulin use. There were no cases of maternal hypoglycemia or severe ketosis. Intrapartum CBG >7.2 mmol/L was associated with third-trimester glycated hemoglobin ( P = .02) and lack of endocrinologic follow-up ( P = .04). Risk of neonatal hypoglycemia was related with pregnancy insulin use compared with dietary control (60.5% vs 29.5%; P = .02).
Conclusion
Peripartum metabolic control in GDM patients was achieved without insulin in most cases. Intrapartum glycemic control was related with third-trimester glycated hemoglobin and with no endocrinologic follow-up. Neonatal hypoglycemia was associated with insulin use during pregnancy.
Gestational diabetes mellitus (GDM) occurs in 2-9% of pregnancies and is associated with elevated rates of maternal and perinatal complications. Intensive treatment of hyperglycemia during pregnancy has been shown to reduce perinatal morbidity. In women with pregestational diabetes (type 1 or 2), hyperglycemia during labor and delivery is an important factor in the development of neonatal hypoglycemia. Previous studies show that strict intrapartum glycemic control reduces the rate of neonatal hypoglycemia and use of insulin infusions is recommended to this effect. However, no generally accepted recommendations exist for women with GDM, given a lack of clinical studies on this topic. Some authors propose the use of intrapartum protocols designed for women with type 1 diabetes mellitus, involving frequent use of insulin drips and greater complexity in labor management. Other recent studies evaluating patients with pregestational diabetes and GDM point out that many of these women do not require insulin during labor to maintain proper glycemic control. These findings suggest that these patients can be managed using a more conservative approach.
Existing practice at our institution was to apply to GDM cases the same intrapartum protocols used for women with type 1 diabetes mellitus. Based on a review of data provided by previous studies, we developed a new protocol for peripartum metabolic control specifically designed for women with GDM.
A study was designed and conducted to evaluate: (1) metabolic control achieved during labor using the new protocol; (2) the effect on intrapartum glycemic control of treatment during gestation and other maternal factors; and (3) the relationship between maternal factors during pregnancy and labor and the risk of neonatal hypoglycemia.
Materials and Methods
Study population
A prospective observational study was conducted at Hospital del Mar, Barcelona, from October 2006 through March 2009. All women admitted to our institution for delivery who were diagnosed with GDM, according to the criteria of the Third International Workshop-Conference on GDM, were invited to participate. Multiple pregnancies were excluded.
Prenatal GDM care at our institution is provided by endocrinologists. The protocol includes medical nutrition therapy, daily self-monitoring of capillary blood glucose (CBG), insulin therapy if >20% of readings fall out of target range (fasting CBG >5 mmol/L, 1 hour postprandrial >6.6 mmol/L), determination of glycated hemoglobin (HbA1c), and weekly follow-up visits to adjust treatment. Patients who made <3 follow-up visits were classified as having no endocrinologic follow-up (NEF-GDM). NEF-GDM women were those who did not complete their scheduled visits or were first seen by the endocrinologist at >36 weeks of gestational age.
Study recruitment was done by the primary investigator (J.A.F,). The study was approved by the institutional review board (Comité Etic d′investigació clínica, Institut Municipal d’Assistencia Sanitaria, Barcelona) and each participant signed written informed consent.
Protocol for intrapartum metabolic control of GDM
A new protocol designed for GDM patients was applied upon arrival at the obstetric ward ( Figure ). Based on data from previous studies of women with pregestational diabetes, 7.2 mmol/L was established as the upper limit for target maternal CBG; a maternal CBG below this limit does not increase the risk of neonatal hypoglycemia. Glucose requirements were calculated following the United Nations Food and Agriculture Organization recommendations for a third-trimester pregnant woman (0.10-0.12 g/kg/h, 175-180 g/d) and adjusted according to the number of fasting hours and development of ketosis. Ketone bodies were measured by β-hydroxybutyrate determination in a capillary blood sample. Intrapartum CBG and capillary blood ketone (CBK) measurements were obtained using a blood glucose and ketone monitoring system (Precision Xtra; Abbott Laboratories, Abbott Park, IL). CBG and CBK were measured every 2 hours. If an insulin drip was started, CBG was checked hourly.
Maternal hypoglycemia was defined as a CBG value <3 mmol/L. The last reading before delivery was recorded as maternal delivery CBG. A CBK measurement >1 mmol/L was considered ketosis.
The protocol was carried out by trained midwives, who were advised to contact the physician on call in case of doubts, symptomatic maternal hypoglycemia, or persistent hyperglycemia or ketosis.
Data on newborns were collected at birth, including weight, Apgar score at 1 and 5 minutes, and pH values in umbilical cord artery and vein. Management of the newborn included early feeding and CBG measurements at birth and at 1, 2, 4, 8, 12, 18, and 24 hours thereafter.
Parameters analyzed were: (1) metabolic control during labor, characterized by mean maternal CBG, maternal delivery CBG, number of women with any CBG >7.2 mmol/L, need for insulin treatment (and dosage), hypoglycemic episodes, and presence of ketosis (including mean ketonemia and time to normalization); (2) treatment received during pregnancy: dietary alone, diet plus insulin, or NEF-GDM; (3) intrapartum glycemic control: any maternal CBG >7.2 mmol/L vs no reading >7.2 mmol/L; and (4) neonatal hypoglycemia, defined as any CBG <2.2 mmol/L during the first 24 hours of life.
Statistical analysis
For normally distributed variables, continuous data are presented as means ± SD. For nonnormal distributions, data are presented as median and range. For normally distributed variables, unpaired Student t test and 1-way analysis of variance were used to compare continuous variables and χ 2 or Fisher’s exact test to compare proportions, with an α value of 0.05 in each case. Nonnormally distributed values were compared using the Kruskal-Wallis and Mann-Whitney U tests. Linear regression was used to assess the possibility of correlation between neonatal glycemia and maternal delivery CBG. All statistical analyses were performed using software (SPSS v17; SPSS, Inc, Chicago, IL).
Results
During the 29 months of the study, 139 patients were included. Complete information on intrapartum glycemic control could not be obtained for 10 women, who were then excluded. In 2 newborns, glycemic records for the first 24 hours of life were unavailable. Therefore, the analysis included 129 mothers and 127 newborns.
Maternal and delivery characteristics by treatment received during pregnancy are shown in Table 1 . No differences in maternal and delivery characteristics were observed between study groups.
| Characteristic | Total GDM (n = 129) | Diet-GDM (n = 70) | Insulin-GDM (n = 41) | NEF-GDM (n = 18) | P value |
|---|---|---|---|---|---|
| Age, y | 33.1 ± 5.8 | 32.4 ± 6.1 | 34.5 ± 5.9 | 32.8 ± 4.7 | .21 |
| Caucasian, n (%) | 56 (43.4) | 35 (50) | 17 (41.4) | 4 (22.2) | .10 |
| Pregestational BMI, kg/m 2 | 26.5 ± 4.9 | 26.2 ± 5.5 | 27.1 ± 3.7 | 26.6 ± 5.4 | .67 |
| Nulliparous, n (%) | 67 (51.9) | 36 (51.4) | 24 (58.5) | 7 (38.9) | .37 |
| Third-trimester HbA1c, % | 4.67 ± 0.42 | 4.6 ± 0.41 | 4.7 ± 0.41 | a 5.1 ± 0.45 | .14 |
| Pregnancy weight gain, kg | 9.6 ± 4.3 | 9.7 ± 4.3 | 8.9 ± 3.6 | 12.8 ± 6.1 | .09 |
| Gestational age at delivery, wk | 39.1 ± 1.5 | 39.0 ± 1.6 | 39.3 ± 1.1 | 39.3 ± 2.0 | .44 |
| Preterm delivery, n (%) | 7 (5.4) | 3 (4.3) | 2 (4.9) | 2 (11.1) | .47 |
| Induced labor, n (%) | 47 (36.4) | 23 (32.9) | 19 (46.3) | 5 (27.8) | .37 |
| Cesarean delivery, n (%) | 43 (33.6) | 21 (30) | 16 (39) | 6 (35.3) | .86 |
| Programmed, n (%) | 11 (8.7) | 5 (7.1) | 5 (12.2) | 1 (5.9) | .59 |
| Emergency, n (%) | 32 (24.9) | 16 (22.9) | 11 (26.8) | 5 (29.4) | .81 |
| Newborn weight, kg | 3319 ± 511.6 | 3261 ± 506.2 | 3380 ± 494.2 | 3406 ± 570.5 | .37 |
| Newborn weight >4000 g, n (%) | 12 (9.4) | 5 (7.1) | 3 (7.7) | 4 (22.2) | .16 |
| 1-min Apgar score, median (range) | 9 (7–9) | 9 (7–9) | 9 (7–9) | 9 (7–9) | .66 |
| 5-min Apgar score, median (range) | 10 (9–10) | 10 (9–10) | 10 (9–10) | 10 (9–10) | .46 |
| Umbilical cord arterial pH | 7.25 ± 0.06 | 7.26 ± 0.06 | 7.25 ± 0.06 | 7.26 ± 0.06 | .91 |
| Umbilical cord vein pH | 7.31 ± 0.06 | 7.31 ± 0.06 | 7.32 ± 0.08 | 7.32 ± 0.06 | .59 |
| Neonatal hypoglycemia, n (%) | 15 (11.8) | 5 (7.3) | 9 (21.9) | 1 (5.6) | .02 |
| Neonatal jaundice, n (%) | 3 (2.4) | 2 (2.9) | 1 (2.5) | 0 (0) | .77 |
| NICU admission, n (%) | 15 (11.8) | 8 (11.4) | 5 (12.2) | 2 (11.1) | .99 |
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