Contraceptive use dynamics research needs post fertility transition

Brazil, like many countries in the world today, has very low fertility and high contraceptive use. The TFR is now 1.8, below replacement level, and over 97% of sexually active women age 15-49 have used contraception at some time in their lives (BRASIL, 2008a). Despite the near universality of contraceptive use in Brazil today, 29.7% of births in the five years before the 2006 PNDS were reported as mistimed (wanted later) and 17.8% were reported as unwanted (BRASIL, 2008a). Similar patterns are observed in other low fertility, high contracepting populations; for example, in the United States 99% of women who have ever had sex have used contraception, yet one half of births in the US are unintended (MOSHER; JONES, 2010). In these contexts, a large proportion of unintended pregnancy is the result of contraceptive failure and inconsistent contraceptive use (BLANC; CURTIS; CROFT, 2002; BRADLEY; CROFT; RUTSTEIN, 2011). A large proportion of induced abortions are also preceded by contraceptive use in Brazil (BRASIL, 2008b). Contraceptive discontinuation rates are high for most reversible methods. In Brazil in 1996, the most recent year for which data are available, 12 month discontinuation rates ranged from 42.3% among pill users to 62.8% among injectable users (BLANC; CURTIS; CROFT, 2002). In the same study, 12 month discontinuation rates for all reversible methods in Latin America ranged from 42.8% in Bolivia to 62.9% in the Dominican Republic, and in the United States, 46.3% of women who had ever used a contraceptive method reported having discontinued a method because they were dissatisfied with it (MOREAU; CLELAND; TRUSSELL, 2007). Side effects and health concerns are a major reason for discontinuing modern contraceptive methods; 11.8% of pill users and 27.4% of injectable users in Brazil in 1996 discontinued within 12 months due to side effects and health concerns, (LEITE; GUPTA, 2007) making them the largest single reason for discontinuing these methods. In the US, 64.6% of women who discontinued the pill and 72.3% of women who discontinued the injectable did so because of side effects (MOREAU; CLELAND; TRUSSELL, 2007). The picture is a little different for condoms; the main reasons for discontinuation of condoms relate to characteristics of the method such as inconvenience of use, dislike of the method by partners, interference with sexual pleasure, and concerns over the effectiveness of the method (MOREAU; CLELAND; TRUSSELL, 2007). The s t reng th o f mot i va t ion to avoid pregnancy is another important factor. Analyses of the determinants of d iscont inuat ion cons is tent ly show demographic factors such as whether a woman is spacing or limiting births or her age to be more consistent determinants of discontinuation than socio-economic factors such as education or wealth status (CURTIS; BLANC, 1997; BRADLEY; SCHWANDT; KHAN, 2009). Women do not necessarily report births following discontinuation (for reasons other than desire to get pregnant) or failure as unintended (TRUSSELL, 1999; CURTIS; EVENS; SAMBISA, 2011) suggesting that ambivalence about pregnancy intentions plays a contributing role in discontinuation even when women do not explicitly state they are discontinuing contraceptive use in order to get pregnant. In the US, the National Survey of Family Growth has experimented with alternative methods of measuring fertility preferences and Santelli and colleagues have shown that