Antenatal and delivery care in rural western Kenya: the effect of training health care workers to provide "focused antenatal care" oleh Odhiambo Frank O, Sikuku Evallyne S, Hamel Mary J, van Eijk Anna M, Ouma Peter O, Munguti Kaendi M, Ayisi John G, Crawford Sara B, Kager Piet A, Slutsker Laurence