Fertility Responses to Prevention of Mother-to-Child Transmission of HIV

Transcription

1 Fertility Responses to Prevention of Mother-to-Child Transmission of HIV Nicholas Wilson Williams College and University of California, Berkeley

2 PMTCT Probability of transmission from HIV+ mother to child 50% Prevention of mother-to-child transmission (PMTCT) reduces probability to as little as 3% Clinics offering PMTCT in Zambia in 2000 < 6 Clinics offering PMTCT in Zambia in Sub-Saharan Africa: 15% individual coverage in 2005, 54% in 2010

3 Fertility Research question: effect of PMTCT on fertility HIV prevalence among pregnant women = 13.9% (2007 ZDHS) Implies roughly 7% of children born HIV+ or acquire through breastfeeding Infant infected with HIV dies with probability 1/2 by age 1 Total fertility rate (TFR) = 5.91 (Fortson 2009) Suggests 0.40 child deaths due to HIV across woman s lifetime

4 Motivation PMTCT changes incentives that affect reproductive choices Wilson (2012) shows PMTCT scale-up in Zambia reduced all-cause infant mortality by approximately 2 percentage points ( 20 percent) Quantity-quality model (Becker and Lewis 1973) Reduces shadow price of child quantity => fertility Reduces shadow price of child quality => fertility Reduces need for replacement fertility => fertility

5 Existing Literature No economic analyses of behavioral effects of PMTCT HIV/AIDS pandemic has had little-to-no effect on fertility in Sub-Saharan Africa (Fortson 2009, Kalemli-Ozcan and Turan 2010) PMTCT does not reverse pandemic, PMTCT simply reduces child mortality risk associated with HIV/AIDS Fertility responses to changes in child mortality risk (e.g., Ben-Porath 1976, Wolpin 1984, Sah 1991, Soares 2005, Lucas 2010) Behavioral responses to changes in reproductive technology (e.g., Donohue and Levitt 2001, Goldin and Katz 2002, Pop-Eleches 2006, Ashraf et al 2010, Portner 2010, Valente 2010, Ananat and Hungerman 2012)

6 Overview Monthly panel of all health clinics in Zambia Repeated cross-sectional national household surveys (2001 and 2007 DHS, 2003 and 2005 ZSBS) Examine effect of local PMTCT availability on pregnancy, controlling for time and geographic FEs and linear trends Findings: PMTCT reduced local pregnancy rate by 3 to 4 percentage points (baseline 31%) Effect larger closer to clinic where PMTCT locally introduced Effect larger in medium term than in short term Effect larger among women more likely to be HIV positive PMTCT increased breastfeeding by approx percentage points (baseline 80%)

7 Outline PMTCT - medical facts, scale-up Conceptual framework Data and empirical strategy Effect of PMTCT on pregnancy, breastfeeding Distance, timing, HIV prevalence

8 MTCT 10% of new HIV infections are due to mother-to-child transmission (MTCT) 90% of pediatric HIV infections and 94% of pediatric HIV deaths in Sub-Saharan Africa Three channels for MTCT: in utero during childbirth [in utero + childbirth 15-30%] breastfeeding [ 10-20%]

9 Pediatric HIV/AIDS Approx. 400,000 new pediatric HIV infections per year in Sub-Saharan Africa Probability of death by age % Competing risks: HIV/AIDS 12% of under-5 mortality in Zambia

10 PMTCT Counseling and testing for HIV, ARVs to reduce vertical transmission, breastfeeding advice, family planning Zambia: Initially, just counseling and testing for HIV Antiretroviral prophylaxis (ARVs) in early 2000s Breastfeeding advice formalized in 2007 National Protocol Guidelines Family planning formalized in 2010 National Protocol Guidelines

11 PMTCT - Clinical Facts WHO recommendation: Combination therapy (including AZT and NVP) for mothers and infants (i) at diagnosis while pregnant, (ii) at childbirth, (iii) during first 1-2 weeks of breastfeeding Efficacy: Reduces prob. of MTCT from approx. 50% to as little as 3% Standard practice in Zambia: Single-dose NVP for mothers and infants (i) at diagnosis while pregnant, (ii) at childbirth, (iii) during first 1-2 weeks of breastfeeding 93% of pregnant women visit antenatal clinic, but 52% of births at home Clinics provide NVP to take home

12 PMTCT - Scale-up Sub-Saharan Africa: PEPFAR and global partners funded expansion Individual-level coverage: 15% in 2005, 45% in 2008, 53% in 2010 Zambia: Fewer than 6 PMTCT sites in 2000 Nearly 600 PMTCT sites by end of 2007 ( 40% of health facilities)

13 Figure 1: PMTCT Availability in Zambia, cumulative number of PMTCT sites

14 PMTCT Sites Initiated in 2001 or Earlier Ü Kilometers

15 PMTCT Sites Initiated in 2002 and 2003 Ü Kilometers

16 PMTCT Sites Initiated in 2004 and 2005 Ü Kilometers

17 PMTCT Sites Initiated in 2006 and 2007 Ü Kilometers

18 Table 1: Hierarchy of HIV/AIDS Service Expansion December 2001: ART PMTCT VCT number percent number percent number percent (1) (2) (3) (4) (5) (6) All facilities PMTCT sites December 2003: All facilities PMTCT sites December 2005: All facilities PMTCT sites December 2007: All facilities PMTCT sites

19 Conceptual Framework Quantity-quality model (Becker and Lewis 1973) PMTCT increases child survival => price of child quantity => child quantity PMTCT increases return to investment in child quality => price of child quality => child quality => child quantity Replacement/precautionary fertility PMTCT increases proportion of births surviving into adulthood Reduces need for replacement fertility and should reduce TFR Replacement fertility dominates precautionary fertility when uncertainty realized at young child age/while mother still of child-bearing age ARVs or information? ARVs reduce probability of MTCT Pregnant women receives information HIV+ in conjunction with ARVs

20 Timing of PMTCT Effect Let t denote interview month Outcome of interest is pregnant (Y/N) at any point in [t 11, t] Conception likely occurred in [t 20, t 1] If conceptions uniformly distributed across months, then representative conception occurred at approx. t 10

21 Data PMTCT expansion: GPS coordinates of each health facility in Zambia Newly assembled monthly panel of PMTCT scale-up (as well as ART, VCT) Reproductive behavior, etc: Repeated cross-sectional national household surveys and 2007 DHS, 2003 and 2005 ZSBS Pregnant (Y/N) in twelve months leading to survey month, breastfeeding (Y/N) conditional on child age 0-24 months GPS coordinates of centroid of Statistical Enumeration Area (SEA) of residence for each respondent (approx. 15,000 SEAs in Zambia) Interview month for each respondent (approx. 5 months per survey round)

22 Table 2: Mean Characteristics of Female DHS and ZSBS Respondents by Age and Education Age number of children HIV currently pregnant ever born positive breastfeeding (1) (2) (3) (4) All females Observations 17,820 17,805 5,698 5,507

23 Table 3: Mean Characteristics of Female DHS and ZSBS Respondents by Proximity to PMTCT Site Sample: Panel A: Females age within 20km greater than 20km of eventual PMTCT site from eventual PMTCT site (1) (2) Age Completed primary Completed secondary Married Any partner Sex in past month Proportion unprotected s Pregnant Number of children HIV positive Observations 13,747 4,073 Panel B: Children age 0-24 months Breastfeeding Observations 3,996 1,511

24 Empirical Strategy Rapid scale-up of PMTCT + time/geographic controls => quasi-experimental evidence Examine effect of local PMTCT availability on pregnant (Y/N), breastfeeding (Y/N) conditional on child age 0-24 months Control for: Whether location ever offered PMTCT Month and year FEs PMTCT expansion stage Individual-level controls (i.e., primary school, secondary school, married, five-year age group) Province FEs Province-specific linear trends Additional linear trend for locations ever receiving PMTCT Local availability of other HIV/AIDS services (i.e., ART and VCT) Household access to piped water, household bed net ownership

25 Empirical Strategy pregnant ijmt = α 1 P ij(mt 11) + α 2 Pever ij + α 3 Plate ij + X ijmt Γ + η j + ψ m + δ t + mtµ j + mtpever ij + ɛ ijmt P ij(mt 11) indicates clinic located near respondent i offered PMTCT at least 11 months prior to survey date Pever ij indicates clinic located near respondent i ever offered PMTCT Pearly ij indicates clinic located near respondent i introduced PMTCT after December 2004 is vector of individual-level demographic controls, controls for ART and VCT availability, controls for piped water and bed net X ijt η j are province FEs, ψ m are month FEs, δ t are year FEs mtµ j is vector of province-specific time trends, mtpever ij is linear trend for locations ever receiving PMTCT

26 Table 4: Effect of Local PMTCT on Reproductive Behavior Dependent variable: pregnant (1) (2) (3) (4) (5) (6) PMTCT within 20km *** *** *** *** *** (0.011) (0.012) (0.014) (0.010) (0.013) (0.017) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 17,820 17,819 17,819 17,817 17,817 15,734 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

27 Table 4: Effect of Local PMTCT on Reproductive Behavior Dependent variable: breastfeeding (1) (2) (3) (4) (5) (6) PMTCT within 20km 0.037** 0.095*** 0.136*** 0.139*** 0.201*** 0.227*** (0.015) (0.018) (0.021) (0.021) (0.029) (0.030) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 5,507 5,507 5,507 5,507 5,507 5,507 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

28 Table 5: Spatial Heterogeneity in Effect of Local PMTCT on Reproductive Behavior Dependent variable: pregnant (1) (2) (3) (4) (5) (6) PMTCT within 10km *** *** *** * ** (0.017) (0.017) (0.017) (0.014) (0.014) (0.015) PMTCT within 20km (0.029) (0.028) (0.027) (0.021) (0.021) (0.022) PMTCT within 30km (0.026) (0.026) (0.026) (0.019) (0.019) (0.019) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 17,820 17,819 17,819 17,817 17,817 15,734 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

29 Table 5: Spatial Heterogeneity in Effect of Local PMTCT on Reproductive Behavior Dependent variable: breastfeeding (1) (2) (3) (4) (5) (6) PMTCT within 10km (0.027) (0.027) (0.026) (0.026) (0.025) (0.025) PMTCT within 20km 0.051** 0.103*** 0.139*** 0.137*** 0.198*** 0.215*** (0.022) (0.023) (0.025) (0.024) (0.029) (0.030) PMTCT within 30km (0.037) (0.034) (0.034) (0.034) (0.033) (0.030) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 5,507 5,507 5,507 5,507 5,507 5,507 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

30 Figure 3: Semi-Parametric Difference-in-Differences Analysis of Effect of Local PMTCT on Fertility with controls no controls event time in months

31 Table 6: Dynamic Effects of Local PMTCT on Reproductive Behavior Dependent variable: pregnant (1) (2) (3) (4) (5) (6) PMTCT within 20km ** *** *** *** *** (0.013) (0.013) (0.014) (0.011) (0.013) (0.017) PMTCT within 20km at least 36 months ** *** * * (0.014) (0.014) (0.014) (0.011) (0.013) (0.014) P > F(PMTCT+PMTCT 36 months=0) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 17,820 17,819 17,819 17,817 17,817 15,734 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

32 Table 6: Dynamic Effects of Local PMTCT on Reproductive Behavior Dependent variable: breastfeeding (1) (2) (3) (4) (5) (6) PMTCT within 20km 0.051*** 0.105*** 0.137*** 0.140*** 0.201*** 0.225*** (0.018) (0.019) (0.020) (0.020) (0.027) (0.028) PMTCT within 20km at least 36 months (0.023) (0.024) (0.027) (0.026) (0.038) (0.040) P > F(PMTCT+PMTCT 36 months=0) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 5,507 5,507 5,507 5,507 5,507 5,507 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

33 Table 7: Heterogeneity by HIV Prevalence in Effect of Local PMTCT on Reproductive Behavior Dependent variable: pregnant (1) (2) (3) (4) (5) (6) PMTCT within 20km ** *** *** (0.018) (0.019) (0.021) (0.015) (0.017) (0.021) PMTCT within 20km * HIV prevalence ** (0.086) (0.084) (0.084) (0.069) (0.076) (0.082) P > F(PMTCT+PMTCT * HIV prev=0) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 17,818 17,817 17,817 17,817 17,817 15,734 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

34 Table 7: Heterogeneity by HIV Prevalence in Effect of Local PMTCT on Reproductive Behavior Dependent variable: pregnant (1) (2) (3) (4) (5) (6) PMTCT within 20km *** *** *** * * (0.014) (0.015) (0.016) (0.012) (0.013) (0.018) PMTCT within 20km * HIV prevalence ** ** * at median or above (0.016) (0.016) (0.016) (0.013) (0.014) (0.015) P > F(PMTCT+PMTCT * HIV prev=0) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 17,818 17,818 17,817 17,817 17,817 15,734 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

35 Table 8: Heterogeneity by HIV Prevalence in Effect of Local PMTCT on Reproductive Behavior Dependent variable: breastfeeding (1) (2) (3) (4) (5) (6) PMTCT within 20km *** 0.132*** 0.147*** 0.204*** 0.229*** (0.028) (0.030) (0.032) (0.031) (0.041) (0.042) PMTCT within 20km * HIV prevalence (0.137) (0.137) (0.136) (0.137) (0.157) (0.156) P > F(PMTCT+PMTCT * HIV prev=0) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 5,507 5,507 5,507 5,507 5,507 5,507 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

36 Table 8: Heterogeneity by HIV Prevalence in Effect of Local PMTCT on Reproductive Behavior Dependent variable: breastfeeding (1) (2) (3) (4) (5) (6) PMTCT within 20km 0.047** 0.108*** 0.143*** 0.147*** 0.207*** 0.233*** (0.021) (0.023) (0.025) (0.025) (0.033) (0.035) PMTCT within 20km * HIV prevalence at median or above (0.026) (0.026) (0.026) (0.026) (0.028) (0.028) P > F(PMTCT+PMTCT * HIV prev=0) Year and month fixed effects NO YES YES YES YES YES Control for PMTCT expansion stage NO NO YES YES YES YES Individual level controls NO NO NO YES YES YES Province fixed effects and linear trends NO NO NO NO YES YES Controls for other HIV/AIDS services, piped water, and bed net ownership NO NO NO NO NO YES Observations 5,507 5,507 5,507 5,507 5,507 5,507 *** Significant at the 1 percent level, ** 5 percent level, * 10 percent level. Standard errors are in parentheses and are clustered by Standard Enumeration Area (SEA).

37 Conclusion Newly assembled monthly panel of health facilities in Zambia First detailed documentation of PMTCT scale-up for an entire high HIV prevalence country Examine fertility responses to local PMTCT availability Key findings: Local PMTCT reduced pregnancy rate by 3 to 4 percentage points Larger change closer to clinic Larger change in medium term than in short term Larger change among women more likely to be HIV positive Breastfeeding increased by 5 to 20 percentage points Decrease in child quantity and increase in child quality Short-term vs. long-term response A 10% reduction in TFR implies approx. 0.5 child reduction in TFR

38 Thank You Thank you!