Influence of weight gain, according to Institute of Medicine 2009 recommendation, on spontaneous preterm delivery in twin pregnancies

Table 1 Population general characteristics, according to weight gain groups

	Under (91)	Normal (73)	Over (11)	P value
Maternal age	34 ± 5.55	34 ± 5.86	34 ± 5.03	0.99
Nulliparity	52 (57.1%)	44 (60.3%)	8 (72.7%)	0.32
Smoker	3 (3.9%)	5 (6.8%)	1 (9.1%)	0.38
Chronic Hypertension	1 (1.1%)	1 (1.4%)	0	0.93
pBMI^a	22.75 ± 4.44	23.00 ± 3.29	23.97 ± 2.50	0.70
18.5 ≤ pBMI^a ≤ 24.9	74 (81.3%)	54 (74.0%)	6 (54.5%)	0.11
25 ≤ pBMI^a ≤ 29.9	10 (11.0%)	15 (20.5%)	5 (45.5%)	0.01
pBMI^a ≥ 30	7 (7.7%)	4 (5.5%)	0	0.57
Medically assisted procreation	16 (17.6%)	18 (24.7%)	4 (36.4%)	0.26
Mono- Chorionicity	13 (14.3%)	11 (15.1%)	2 (18.2%)	0.94
Clinical chorionamnionitis	1 (1.1%)	0	0	0.63
Preterm rupture of membranes^b	30 (33.0%)	13 (17.8%)	3 (27.3%)	0.09
Gestational age at delivery (weeks)	35.3 ± 3.0	36.5 ± 2.0	35.3 ± 2.0	0.002
Vaginal delivery	34 (37.4%)	23 (31.5%)	4 (36.4%)	0.73
1^st twin birth weight (gr)	2196.54 ± 592.16	2494.11 ± 426.87	2374.55 ± 471.63	0.002
2^nd twin birth weight (gr)	2154.89 ± 499.41	2392.95 ± 413.94	2443.50 ± 334.47	0.002

Results are reported as means and standard deviations (continuous factors) or numbers and percentages (categorical factors). The p-value of an overall test comparing the three groups is also provided (One-way ANOVA for continuous factors and Chi-square test for categorical factors)
Italic data are statistically significant
^apBMI = pre-gestational Body Mass Index; ^bPreterm rupture of membrane = rupture before 37 weeks

ISSN: 1471-2393