Columbia subject headings:
Birth control--Research.
Breastfeeding--Research.
Contraception--Research.
Fertility, Human--Research.
Harvard subject headings:
Princeton subject headings:
Breastfeeding--Colombia.
Breastfeeding--Costa Rica.
Breastfeeding--Mathematical models.
Contraception--Colombia.
Contraception--Costa Rica.
Contraception--Mathematical models.
Fertility, Human--Colombia.
Fertility, Human--Costa Rica.
Fertility, Human--Mathematical models.