In utero exposure to extra vitamin D from food fortification and the risk of subsequent development of gestational diabetes: the D-tect study

Table 1 Characteristics of women prenatally exposed and unexposed to vitamin D fortified margarine and their offspring

	Exposed		Unexposed		p-value
	N	Median (5,95 percentiles)	N	Median (5,95 percentiles)
Age at delivery^a,c	14,016	25.2 (21.4;27.3)	14,855	25.1 (21.2;27.3)	< 0.0001
Gestational sunshine hours^a,c,e	14,016	1108 (752;1311)	14,855	1004 (772;1320)	< 0.0001
Offspring’s birth weight (g) ^b,d	14,016	3460 (2572;4270)	14,855	3455 (2560;4260)	0.3
		Percentage		Percentage
Gestational diabetes mellitus^a	297	2.1	361	2.4	0.08
Pre-pregnancy BMI^a,d					0.01
< 18.5 kg/m²	636	4.5	800	5.4
18.5–24.9 kg/m²	8514	60.7	8860	59.6
25–29.9 kg/m²	2984	21.3	3154	21.2
≥ 30 kg/m²	1882	13.4	2041	13.7
Size for gestational age^a					0.7
SGA	1741	12.4	1891	12.7
NGA	11,299	80.7	11,961	80.6
LGA	955	6.8	990	6.7
Birth weight (g)^a,d					0.8
< 2500	570	4.1	593	4.0
2500–4000	11,536	82.3	12,274	82.6
≥ 4000	1910	13.6	1988	13.4
Smoking status during pregnancy^a,d					< 0.0001
Current smoker	2170	15.8	1911	13.0
Former smoker	715	5.2	827	5.6
Non-smoker	10,890	79.1	11,935	81.3
Season of birth^d					0.8
Winter	3214	23.0	3465	23.3
Spring	3568	25.5	3722	25.1
Summer	3675	26.2	3875	26.1
Autumn	3559	25.4	3793	25.5
Offspring’s gestational age at delivery (weeks)^b,d					< 0.0001
< 37	871	6.2	892	6.0
37 + 0–37 + 6	699	5.0	727	4.9
38 + 0–38 + 6	1688	12.0	1751	11.8
39 + 0–39 + 6	3068	21.9	3150	21.2
40 + 0–40 + 6	4033	28.8	4423	29.8
41 + 0–41 + 6	2819	20.1	3414	23.0
≥ 42	838	6.0	498	3.4
Offspring’s gender^b,d					0.02
Female	6920	49.4	7128	48.0
Male	7096	50.6	7727	52.0

^aCharacteristics of women prenatally exposed and unexposed to vitamin D fortified margarine and ^b their offspring
^ctested by Mann-Whitney rank-sum test and ^d tested by X²-test
^eSummary monthly sunshine hours during the nine months prior to the month of birth, bounded to each individual

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