Table 2.

Infant characteristics and the prevalence of pre-pregnancy BMI.

Characteristics	BMI < 18.5 kg/m2 (n = 54,238)			18.5 kg/m2 ≤ BMI < 24.0 kg/m2 (n = 282,480)		24.0 kg/m 2 ≤ BMI < 28.0 kg/m 2(n = 51,251)			BMI ≥ 28.0 kg/m 2 (n = 10,399)			total		X2	P
	n	%	Prevalence	n	%	n	%	Prevalence	n	%	Prevalence	n	%
			(%)					(%)			(%)
Childbirth
Vaginal birth	42,968	79.22	14.77	210,973	74.69	31,793	62.03	10.93	5172	49.73	1.78	290,906	73.02	7459.063	< 0.001
Cesarean-section	11,270	20.78	10.49	71,507	25.31	19,458	37.97	18.11	5227	50.27	4.86	107,462	26.98
Sex
Male	28,200	51.99	13.48	148,326	52.51	27,184	53.04	12.99	5506	52.95	2.63	209,216	52.52
Female	25,985	47.91	13.77	133,855	47.39	24,009	46.85	12.72	4876	46.89	2.58	188,725	47.37	16.451	< 0.001
Unknown	53	0.1	12.41	299	0.11	58	0.11		17	0.16		427	0.11
Outcome
Survival	54,027	99.61	13.62	281,182	99.54	50,991	99.49	12.86	10,337	99.4	2.61	396,537	99.54
Stillbirth	188	0.35	11.92	1119	0.4	218	0.43	13.82	52	0.5	3.3	1577	0.4	17.047	< 0.001
Died 7 days after birth	16	0.03	8.12	140	0.05	34	0.07	17.26	7	0.07	3.55	197	0.05
Died between 7 and 42 days after birth	7	0.01	12.28	39	0.01	8	0.02	14.04	3	0.03	5.26	57	0.01
Gestational weeks	38.96 ± 1.63			38.96 ± 1.66		38.89 ± 1.75			38.80 ± 1.81			38.94 ± 1.67		55.179	< 0.001
Birth weight	3262.61 ± 365.45			3284.84 ± 369.02		3304.88 ± 384.42			3314.41 ± 410.55			3284.84 ± 372.04		149.441	< 0.001