Table 1.

Baseline characteristics of study population according to chorionicity.

	Monochorionic n=105	Dichorionic n=219	p
Maternal characteristics
Age (yr), mean ± SD	26.9 (6.68)	29.58 (6.45)	0.01*
Stature (m), mean ± SD	1.60 (0.06)	1.61 (0.06)	0.37*
White ethnicity, n (%)	61 (58.1)	115 (52.5)	0.40#
Multiparous, n (%)	19 (18.1)	72 (32.9)	0.006#
Smoking during pregnancy, n (%)	11 (10.5)	41 (18.7)	0.05#
Alcohol abuse during pregnancy, n (%)	0 (0)	5 (2.3)	0.18§
Illicit substance use during pregnancy, n (%)	1 (1)	8 (3.7)	0.28§
Medical disorders prior to pregnancy, n (%)**	28 (26.7)	47 (21.6)	0.33#
Gestational complications	20 (19)	59 (26.9)	0.13#
Perinatal characteristics
Twin growth restriction, n (%)	40 (38.1)	57 (26)	0.04#
Birth weight discordance (%), mean ± SD	15.63 (13.51)	12.3 (11.05)	0.03*
Gestational age at delivery, mean ± SD	34.45 (2.55)	35.55 (2.89)	0.001*
Total birth weight (g), mean ± SD	3913.98 (919.17)	4537.36 (1106.89)	<0.001*
Placental characteristics
Total placental weight (g), mean ± SD	645.94 (133.02)	730.33 (186.39)	<0.001*
Birth weight/placental weight ratio	6.12 (1.16)	6.32 (1.18)	0.17
Number of lesions, mean ± SD	0.60 (0.83)	0.57 (0.75)	0.79*

SD, standard deviation; yr, years.

^*Student’s t test;

^#Chi-square test;

^§Fisher’s exact test

^**Medical disorders prior to pregnancy: chronic hypertension, diabetes, asthma, cardiopathy, hypothyroidism, thrombophilia, or chronic kidney disease.