Table 1.

Subject characteristics (n = 189 mother-infant dyads).

Maternal variables	N (%) or Mean [Range]
Maternal age	31.9 [20–43.7]
Pre-pregnancy BMIa	25.8 [17.4–44.2]
Underweight	4 (2.1)
Normal	105 (55.6)
Overweight	44 (23.3)
Obese	35 (18.5)
Gestational weight gain (lbs)b	31.9 [−4–75]
Paritya	1.8 [1–5]
One	90 (47.6)
Two or more	98 (51.9)
Delivery mode
Vaginal	138 (73.0)
Cesarean section	51 (27.0)
Race
Non-Hispanic White	181 (95.8)
Asian	1 (0.5)
Black	1 (0.5)
Hispanic White	6 (3.2)
Educationc
High school graduate or equivalent	16 (8.5)
Some college or technical school	28 (14.8)
College graduate	64 (33.9)
Any post-graduate schooling	74 (39.2)
Prenatal antibioticsd
No	135 (71.4)
Yes	36 (19.0)
Peripartum antibioticsc
No	88 (46.6)
Yes	94 (49.7)
Antibiotics by 4 months postpartume
No	140 (74.1)
Yes	20 (10.6)
Antibiotics by 8 months postpartumf
No	119 (63)
Yes	30 (15.9)
Antibiotics by 8 months postpartumg
No	102 (54)
Yes	41 (21.7)
Infant variables	N (%) or Mean [Range]
Sex
Female	89 (47.1)
Male	100 (52.9)
Perinatal antibioticsh
No	176 (93.1)
Yes	4 (2.1)
Gestational age at birth (weeks)	39.3 [30–43.4]
Birth weight (grams)h	3466.5 [2296–4,710]
Antibiotics by 4 months of agei
No	155 (82)
Yes	6 (3.2)
Antibiotics by 8 months of agej
No	123 (65.1)
Yes	27 (14.3)
Antibiotics by 12 month of ageg
No	87 (46)
Yes	56 (29.6)
Feeding method through 4 months of agek
Unexposed to formula	113 (59.8)
Exposed to formula	51 (27.0)
Feeding method through 8 months of agel
Unexposed to formula	79 (41.8)
Exposed to formula	77 (40.7)
Feeding method through 12 months of agef
Unexposed to formula	42 (22.2)
Exposed to formula	107 (56.6)

Number of subjects with missing data: ^a1, ^b2, ^c7, ^d18, ^e29, ^f40, ^g46, ^h9, ⁱ28, ^j39, ^k25, ^l33.