Cluster 117: lactation pregnancy breastfeeding test positive current year women standards time Cluster 872: breastfeeding pregnancy current active women reported self planning possibility intention Cluster 941: breastfeeding pregnancy test negative pregnant entry days study childbearing women Cluster 1078: pregnancy pregnant test women positive breastfeeding serum lactating study urine Cluster 1277: pregnant planning feeding breast breastfeeding study months pregnancy female lactating Cluster 1781: feeding pregnancy breast test positive unwillingness women known urine effective Cluster 2219: breastfeeding women lactating study participants eligible registration time zydelig fancd Cluster 2251: pregnancy test positive women serum administration enrollment product wocbp urine