The dynamics of birth spacing and marital fertility in Kenya.

Data from the 1978 Kenya Fertility Survey were used to estimate levels of fecundity and birth intervals to assess the relative contributions of breastfeeding lactational amenorrhea and the menstruating interval to birth spacing and marital fertility among women aged 15-44. The data demonstrate how social and cultural factors operate on intermediate variables to produce differentials in marital fertility and also indicate that modernization is resulting in higher fertility in some cases. The marital fertility rate is 399 for women under 25 338 for those 25-34 and 196 for those 35-44 and in each age group the proportion of women progressing to the next pregnancy is lower. 97% of women breastfeed their babies for a mean duration of 17 months. Postpartum abstinence averages only 3 months. 4% of women reported current use of an effective contraceptive method but their mean menstruating interval was only 8 months. The fertility of the approximately 30% of wives in polygamous unions is 11% lower than that of wives in monogamous unions with earlier wives having lower fertility. After age adjustment women with some schooling have a fertility rate 4% higher than those with no schooling. 48% of the wives had some education limited among 88% to primary school. Rising female education is associated with progressively shorter durations of breastfeeding and lactational amenorrhea as well as lower proportions in polygamous unions. For married women under 35 fertility is higher among the educated. Women whose husbands are in technical white collar or professional occupations also have shorter durations of breastfeeding than women whose husbands are in traditional agricultural occupations. Only among women over 35 is there evidence that higher levels of contraceptive practice compensate sufficiently for the decline in traditional fertility-restricting practices to produce a net fertility decline. Among women under 25 fertility is slightly higher in urban areas due to shorter breastfeeding but by age 35-44 fertility is 72% lower among urban residents. Fecundity impairments presumably due to poor health are important causes of regional variation in fertility in the rural areas.