Table I.

Baseline characteristics of the VIRTUAL placenta subcohort, stratified for the mode of conception.

	IVF/ICSI Frozen-thawed ET n = 32		IVF/ICSI Fresh ET n = 56		Natural conception n = 126
	Median/N	IQR/%	Median/N	IQR/%	Median/N	IQR/%	P-value	Missing
Maternal characteristics
Age, years	33.3	29.4–36.4	33.1	29.3–36.2	31.4	28.8–34.5	0.098	0
Body mass index, kg/m2	24.2	21.9–28.4	23.9	21.8–27.3	25.3	22.5–29.7	0.118	0
MAP, mmHg	82.5	76.7–88.2	80	76.7–83.3	80	75.3–85.1	0.202	0
Nulliparous	23	71.9	45	81.8	50	39.7	<0.001d,e	1
Geographical origin, Western	23	71.9	50	90.9	98	77.8	0.048c,e	0
Education							0.698	6
Low	4	12.5	4	7.3	10	8.3
Middle	8	28.1	22	40.0	38	31.4
High	19	59.4	29	52.7	73	60.3
Alcohol, yesa	13	40.6	10	17.9	34	27.0	0.067	0
Smoking, yesb	7	21.9	5	8.9	16	12.7	0.219	0
Folic acid, yesb	30	93.8	56	100	92	73.6	<0.001d,e	1
Fertilisation method, ICSI	15	46.9	38	67.9	NA		0.053	0

IQR, interquartile range. MAP, mean arterial pressure.

^aAny use during the 14 weeks prior to up to 10 weeks of gestation.

^bDaily use during the 14 weeks prior to up to 10 weeks of gestation.

^cSignificantly different between pregnancies after frozen-thawed ET and after fresh ET.

^dSignificantly different between pregnancies after frozen-thawed ET and naturally conceived pregnancies.

^eSignificantly different between pregnancies after fresh ET and naturally conceived pregnancies.