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Table 1 Design characteristics of observational studies of glycated haemoglobin and pregnancy outcomes.

From: Poor glycated haemoglobin control and adverse pregnancy outcomes in type 1 and type 2 diabetes mellitus: Systematic review of observational studies

Author Country Study Design Time Period Sample size (n) Glycaemic Control Groupings (n) (HbA 1c unless stated) Timing of Glycaemic Control Measurement Outcomes (n)
Vaarasmaki et al, 2000 [26] Finland Cohort 1986–1995 84 Optimal < 8.0% (n = 48)
Poor > 8.0% (n = 36)
First antenatal visit 20 and 28th week Before delivery Malformations (n = 4)
Caesarean section (n = 34)
Stillbirth (n = 1)
NICU (n = 39)
Neonatal hypoglycaemia(n = 11)
RDS (n = 5)
Greene et al, 1989 [23] US Cohort Dec.5th 1983–Dec.31st 1987 303 Optimal ≤ 9.3% (n = 113)
Poor ≥ 9.4% (n = 190)
(Data based on HbA1)
1st trimester Malformations (n = 20)
Spontaneous abortion (n = 52)
Evers et al, 2004 [16] Netherlands Cohort April 1st 1999 – April 1st 2000 261 Optimal ≤ 7.0% (n = 212)
Poor ≥ 7.0% (n = 71)
1st trimester Malformations (n = 29)
Key et al, 1987 [19]. US Cohort Jan.1st 1979 – Dec.31st 1984 83 Optimal <7.5% (n = 8)
Poor ≥ 7.5% (n = 75)
1st trimester Malformations (n = 9)
Spontaneous abortion (n = 22)
Temple et al, 2002 [7] UK Cohort Jan. 1991–Dec. 2000 158 Optimal < 7.5% (n = 110)
Poor ≥ 7.5% (n = 48)
1st trimester booking Malformations (n = 5)
Stillbirth (n = 2)
Spontaneous abortion (n = 11)
Neonatal death (n = 2)
Kitzmiller et al, 1991 [22] USA Cohort 1982–1988 194 Optimal ≤ 7.6% (n = 53)
Poor > 7.6% (n = 141)
1st trimester booking visit Malformations (n = 13)
Ylinen et al, 1984 [21] Finland Cohort April 1978–Dec. 1982 142 Optimal ≤ 7.9% (n = 63)
Poor >7.9% (n = 79)
Before 16 weeks gestation Malformations (n = 17)
CEMACH, 2005 [25] England, Wales & Northern Ireland Descriptive Cohort March 1st 2002–Feb 28th 2003 2459 Optimal < 7% (n = 962)
Poor ≥ 7% (n = 1497)
1st trimester Malformations (n = 101)
Stillbirths or neonatal deaths (n = 67)
Hiilesmaa et al, 2000 [17] Finland Case-Control 1988 – 1997 587 Optimal ≤ 6.8% (n = 195)
Poor > 6.8% (n = 392)
Early pregnancy Pre-eclampsia (n = 77)
PIH (n = 65)
Hanson et al, 1990 [24] Sweden Case-Control 1982–1985 532 Optimal < 10.1% (n = 490)
Poor ≥ 10.1% (n = 42)
1st trimester Spontaneous abortion (n = 41)
Malformation (n = 21)
Diabetes and Pregnancy Group, France 2003 [15] France Cross-sectional Jan. 2000 – Dec. 2001 435 Optimal < 8.0% (n = 315)
Poor > 8.0% (n = 120)
1st trimester Malformations (n = 18)
Perinatal mortality (n = 19)
Preterm delivery (n = 147)
Miller et al, 1981 [18] US Case-series April 1977 – April 1980 116 Optimal ≤ 8.5% (n = 58)
Poor ≥ 8.6% (n = 58)
Initial value Malformations (n = 15)
Wender-Ozegowska et al, 2005 [20] Poland Case-Series 1st Jan. 1994–31st Jan. 1999 126 Optimal ≤ 5.6% (n = 43)
Poor > 5.6% (n = 83)
1st trimester Malformations (n = 14)