Table 3.
Studies of the association of antepartum A1C and birthweight, macrosomia, large for gestational age (LGA) and fetal macrosomia, by time of A1C measurement and year of publication
| First author | Study design (n) | Inclusion/exclusion | GDM criteria & prevalence n (%) | Time of antepartum A1C measurement and GDM diagnosis | Outcome, prevalence n (%), and findings |
|---|---|---|---|---|---|
| Baxi38 | Cohort (n = 180) | Inclusion: | 100 g OGTT (thresholds not specified) 32 (18) | Time of GDM diagnosis (gestational age not specified) | Macrosomia 10 (31) |
| High risk of GDM | Higher prevalence of macrosomia among GDM patients with A1C ≥ 6.78 | ||||
| Exclusion: | A1C ≥ 6.78: 10 (50) | ||||
| Variant haemoglobin | A1C < 6.78: 0 (0) | ||||
| Morris39 | Cohort (n = 69) | Inclusion: | NDDG 21 (30) | Time of GDM diagnosis (<17 weeks gestation) | LGA 29 (42) |
| Screened at 10–15 weeks gestation and >23 weeks | Higher prevalence of LGA among non-diabetic women with highest A1C | ||||
| A1C <6%: | |||||
| Non-diabetic 4 (10) | |||||
| A1C 6–6.9%: | |||||
| Non-diabetic 6 (75) | |||||
| GDM 4 (40) | |||||
| A1C > 7%: | |||||
| GDM 4 (36) | |||||
| Morris40 | Cohort (n = 64) | Inclusion: | NDDG 15 (23) | Time of GDM diagnosis (10–15 weeks gestation) | LGA 15 (23) |
| Prenatal care Apr 1983-Mar 1984, | Higher prevalence of LGA among women with A1C ≥ 6.3 | ||||
| GDM screen at 10–15 weeks gestation | A1C ≥ 6.3: 9 (44) | ||||
| A1C < 6.3: 6 (14) | |||||
| Exclusion: | |||||
| T2DM | |||||
| Schaefer-Graf41 | Cohort (n = 403) | Inclusion: | WHO 306 (76) | Time of GDM screening (0–40 weeks gestation) | Fetal macrosomia 75 (19) |
| Singleton, | No difference in mean A1C between those with and without fetal macrosomia (P = 0.09) | ||||
| GDM or impaired glucose tolerance, | Fetal macrosomia: 6.08 ± 1.3 | ||||
| Ultrasound at <20 weeks | Normal: 6.2 ± 1.0 | ||||
| Exclusion: | |||||
| Vascular disease, | |||||
| Fetal anomalies | |||||
| Pietryga42 | Cohort (n = 146) | Inclusion: | WHO 146 (100) | Time of GDM diagnosis (24–28 weeks gestation) | LGA 33 (23) |
| GDM, | No difference in mean A1C between those with and without LGA | ||||
| Delivery at 24–40 weeks gestation | LGA: 5.8 ± 1.2 | ||||
| AGA: 5.7 ± 1.0 | |||||
| Lapolla43 | Cohort (n = 611) | Inclusion: | ADA 101 (17) | Time of GDM screening (24–27 weeks gestation) | LGA 85 (14) |
| Screened at 24–27 weeks gestation | Higher A1C associated with increased odds of LGA | ||||
| Exclusion: | OR: 2.76 [95% Cl 0.83, 9.22] | ||||
| Smoking, | |||||
| Chronic hypertension or specific condition effecting metabolism | |||||
| Zawiejska44 | Cohort (n = 357) | Inclusion: | WHO 357 (100) | Time of GDM diagnosis (5–40 weeks gestation) | Birthweight |
| GDM, | A1C and birthweight positively correlated (P < 0.05) | ||||
| Singleton livebirth | r = 0.11 | ||||
| Exclusion: | |||||
| Fetal malformation | |||||
| Seshiah45 | Cohort (n = 207) | Inclusion: | WHO 87 (42) | Time of GDM diagnosis (gestational age not specified) | Birthweight |
| 75 g OGTT | Women diagnosed with GDM at ≤12 weeks gestation compared with women with GDM at >30 weeks had higher A1C mean (SD) 6.93 (1.6) vs. 6.20 (0.3) | ||||
| Exclusion: | Women diagnosed with GDM at ≤12 weeks gestation compared women with GDM at >30 weeks had lower birthweights mean (SD) | ||||
| Pre-gestational diabetes | 3.15 (0.5) vs. 3.51 (0.6) kg | ||||
| Miller46 | Cohort (n = 56) | Inclusion: | NDDG 27 (48) | After GDM diagnosis (third trimester) | Relative birthweight |
| Attending obstetric services | A1C and birthweight not significantly correlated (P ≥ 0.05) | ||||
| r = 0.176 | |||||
| Djelmis47 | Cohort (n = 290) | Inclusion: | WHO 43 (15) | After GDM diagnosis (4 weeks preceding delivery or miscarriage) | Birthweight |
| Treated and delivered 1990–1995 | A1C and birthweight positively correlated (P < 0.05) | ||||
| r = 0.51 | |||||
| Gandhi48 | Cohort (n = 94) | Inclusion: | WHO 67 (71) | After GDM diagnosis (second and third trimester) | ′Birthweight centile’ |
| Diabetes | Higher ‘birthweight centile’ among women with elevated A1C (P = 0.02) | ||||
| Exclusion: | |||||
| Delivery at <36 weeks gestation | A1C < 6.5: 78.9% ± 29.2 | ||||
| A1C > 6.5: 90.2% ± 28.6 |
See text for abbreviations.