Table 2

Characteristics of the study population

	GDM complicated births		Non-GDM births		All births
Characteristic	n	Per cent	n	Per cent	n	Per cent
Age (in years)
<20	45	1.2	2653	4.7	2698	4.5
20–25	288	7.9	9941	17.5	10 229	17.0
25–30	876	24.1	17 593	31.0	18 469	30.6
30–35	1265	34.8	16 480	29.1	17 745	29.4
35–40	876	24.1	8298	14.6	9174	15.2
>40	281	7.7	1710	3.0	1991	3.3
BMI
<18.5 Underweight	61	1.7	1837	3.2	1898	3.1
18.5–25 Normal weight	1091	30.0	27 022	47.7	28 113	46.6
25–30 Overweight	923	25.4	15 217	26.8	16 140	26.8
30–40 Obese	1155	31.8	10 675	18.8	11 830	19.6
>40 Morbid obese	401	11.0	1924	3.4	2325	3.9
Parity
Nulliparous	1452	40.0	24 775	43.7	26 227	43.5
Multiparous	2179	60.0	31 900	56.3	34 079	56.5
Ethnicity
Caucasian	986	27.2	9069	16.0	10 055	16.7
Aboriginal or TSI	94	2.6	1426	2.5	1520	2.5
Asian	695	19.1	5186	9.2	5881	9.8
Other	197	5.4	2457	4.3	2654	4.4
Socioeconomic status
Very low (0–20%)	1074	29.6	14 660	25.9	15 734	26.1
Low (20–40%)	786	21.6	12 020	21.2	12 806	21.2
Medium (40–60%)	695	19.1	11 811	20.8	12 506	20.7
High (60–80%)	549	15.1	9352	16.5	9901	16.4
Very high (<80–100%)	505	13.9	8621	15.2	9126	15.1
Civil status
With stable partner	3296	90.8	49 905	88.1	53 201	88.2
Without stable partner	335	9.2	6770	11.9	7105	11.8
Smoking
At time of conception†	633	17.4	11 314	20.0	11 947	19.8
Second half of pregnancy‡	403	11.1	7780	13.7	8183	13.6
Medical complications
Chronic hypertension	121	3.3	546	0.9	667	1.1
Asthma	270	7.4	3643	6.4	3913	6.4
Fetal sex
Male	1737	47.8	27 631	48.7	29 368	48.7
Female	1895	52.1	29 044	51.2	30 939	51.3

†Analysis of 59 881 subjects (4243 smoking vs 55 638 nonsmoking).
‡Analysis of 59 411 subjects (4213 smoking vs 55 198 nonsmoking).
BMI, body mass index; GDM, gestational diabetes mellitus; TSI, Torres Strait Islander.