Table 1. Baseline characteristics of index pregnancies.

	Twin A		Twin B
Hypertensive disorder in pregnancy in history	Yes, HELLP	No	Yes, HELLP	No
Maternal age, years	27	25	34	32
Nulliparity	Yes	No	Yes	No
Diastolic blood pressure at booking, mmHg	80	75	68	Missing
Highest diastolic blood pressure, mmHg	120	75	120	80
Gestational age at delivery, weeks+days	33+2	40+3	37+4	39+1
Birth weight, grams	1560	4125	3420	3650