-1 = Unknown
0 = No
1 = Yes

Type of delivery
1 = C/S
2 = VAG

Marital Status
1 = Single
2 = Married
3 = Divorced
4 = Widowed

Does mother smoke?
1 = Yes
2 = No

Birth type
-1 = Unknown
1 = Singleton
2 = Twins
3 = Triplets

Breast feeding at discharge
1 = Exclus.
2 = Partial
3 = Supplement
4 = None

Binary coding -- control=0, treatment=1
0 = 0=Control
1 = 1=Treatment

0 = 0=Treatment
1 = 1=Control