Presentation on theme: "This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike License. Your use of this material constitutes acceptance of that license."— Presentation transcript:
1 This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike License. Your use of thismaterial constitutes acceptance of that license and the conditions of use of materials on this site.Copyright 2006, The Johns Hopkins University and W. Henry Mosley. All rights reserved. Use of these materialspermitted only in accordance with license rights granted. Materials provided “AS IS”; no representations orwarranties provided. User assumes all responsibility for use, and all liability related thereto, and must independentlyreview all materials for accuracy and efficacy. May contain materials owned by others. User is responsible forobtaining permissions for use from third parties as needed.
2 Family Planning Policies and ProgramsHenry MosleySession 2 SlidesW. Henry Mosley
4 Measurement of Total Fertility Rate (TFR) Number of births/1000 women(births/women)Age of womenWhere: i = age interval; k = multiplier (1000)
5 Trends in fertility in developing countriesME/NASo. AsiaE. AsiaSS AfricaL. America
6 Trends in Contraceptive Use in Developing CountriesSS Afr.ME/NASo. AsiaL. Amer.E. Asia
7 Relationship Between Fertility and Contraceptive Use 100 countries Surveyed in the 1990sTotal Fertility Rate (TFR)Contraceptive Prevalence (%)Population Reports
8 Fertility Determinants Model Underlying DeterminantsIntermediate (Proximate) DeterminantsFertility
9 Determinants of Fertility Model Bongaarts ProximateDeterminants of Fertility Model
10 Sensitivity of fertility Rating of Intermediate FertilityVariablesIntermediatefertility variablesSensitivity of fertilityto intermediateVariablesVariabilityamongPopulationsOverallRatingProportions married+++Contraceptive usePrevelance of inducedabortion++Postpartum infecundabilityFecundabilitySpontaneous intrauterinemortality+Permanent sterility+++ = High++ = Medium+ = Low or absent
11 Potential Reproductive Life Span ~25 years or300 monthsReproductive potentialAge
12 Model of Reproduction Marriage Sterility Effective reproductive span Birth ofwomanMenarcheMarriagedissolutionDeath ofwomanStart ofsexual unionBirth Birth Birth Birth lastEnd of exposureto riskPostpartuminfecundabilityTime toconceptionPregnancyResumptionof mensesBirth 2ConceptionBirth 3* Effective increase in the average time to the nextconception due to spontaneous fetal losses.
13 A Model of Birth Interval Dynamics Postpartuminfecundity (i)Time to the nextconception (m)Gestation (g)Outcome 1Menses resumesConceptionOutcome 2BirthIntervalModelwith:Postpartuminfecundity(months)Time to nextconceptionGestationTotalintervaleventsin 300monthsMaximum1.59.59.02015Breastfeeding17.5368.3Contraception105.52.8Abortion7.511030
14 Birth Interval Dynamics Model Key Points Breast feeding with lactational amenorrhea is a major determinant of lower fertility in developing countries.Contraception prolongs the “waiting time to conception” by reducing the probability of conception in each ovulatory cycle.Abortion actually shortens the inter-pregnancy interval. Therefore two to three abortions may be required to prevent one live birth.While abortion alone is a very inefficient method of fertility control, abortion with contraceptive backup can be highly efficient.
15 Bongaarts Indices* Postpartum infecundability (Ci) Contraception (Cc) TF(TotalFecundity)Postpartum infecundability (Ci)TNContraception (Cc)and abortion (Ca)(Total NaturalFertility)TMFR(Total MaritalFertility Rate)Marriage (Cm)TFR(Total FertilityRate)*Note: the indices (C) have beendeveloped so that all will have a valueranging from 1.0 signifying no effect ofthe factor, to 0.0 signifying 100%effect.
16 Index of Marriage Not married Married or in sexual union Married TFR = Total Fertility RateTMFR = Total Marital Fertility Rate
17 Index of Contraception Not marriedEffectivelycontraceptingSexual unionand notcontraceptingu = contraceptive prevalencee = contraceptive effectiveness
18 Index of Abortion Not married Effectively contracepting Fertility reductionby abortionTA = Total Abortion Rate
19 Index of Postpartum Infecundabilty Not marriedNot marriedEffectivelycontraceptingFertility reductionby abortionFert. reduction byPP infecundabilitya = duration of postpartumamenorrhea in months (minimun is1.5 months)
20 Hypothetical Model of Bongaarts Indices with the Fertility Transition NonmarriageBreastfeedingAbortionContraceptionTFR
21 Proximate Determinants of Fertility Beijing, 1982NonmarriageSeparationBreastfeedingAbortionContraceptionTFR(Data from: Wang, et al., 1987)
22 Examples of Applications of Bongaarts Indices Bongaarts, J., The fertility inhibiting effects of the intermediate fertility variables. Studies in Family Planning 13: , 1982.Wang, S-X., et al., Proximate determinants of fertility and policy implications in Beijing. Studies in Family Planning 18: , 1987.
24 Relationship of Contraceptive Prevalence to Acceptance and Continuation From epidemiology Prevalence = Incidence x DurationFor contraceptives Contraceptive prevalence = acceptance rate x duration of useThe critical issues in contraceptive programs are:Recruiting acceptorsDropouts by users of “temporary” methods (pills, IUDs, etc.)Failures by all methods, especially user-dependent methods
25 Method Discontinuation Rates IUDOralsCondomsInjectablesNorplantDISCONTINUATION (Range in percent/year)10-30%20-40%25-60%30-40%15-20%
26 Relationship of Discontinuation Rate to Duration of Use(Duration of use = 1/Discontinuation rate)Discontinuation rate/yearDuration of use– 20 years– 10 years– 5 years– 3.3 years– 2.5 years5% (or 0.05)10% (or 0.10)20%30%40%
27 Relationship of Contraceptive Prevalence to Variations in Continuation Rates(Prevalence = Acceptance rate x Continuation)Acceptors = 100/yearPrevalenceContinuation = 4 yearsContinuation = 2 yearsYears
28 Relationship of Contraceptive Prevalence to Variations in Contraceptive Acceptance Rates andContinuation(Prevalence = Acceptance Rate x Continuation)Acceptors = 100/yearPrevalenceAcceptors = 50/yearContinuation = 2 yearsYears
29 Contraceptive Failure Definition – contraceptive failure (F) is a measure of theproportion of women conceiving in a given time period (usuallyone year) while using a method.In general, one can consider the annual failure rate (F) asroughly equal to (1- e) where (e) is contraceptive effectiveness.For example of 100 women using a contraceptive that is 95%effective, 5 (5%) will experience a pregnancy in a year.
30 Contraceptive Failure (Continued) Reported contraceptive failure rates vary widely according to:Method – all methods have an intrinsic failure rate, for example, <0.1% for sterilizations, 0.1% for combined orals, 0.8% for CuT 380A, 2% for condoms, 4% for withdrawal, etc.Characteristics of users - User-dependent methods like condoms, withdrawal and pills, however, can show wide variations in “use-effectiveness” depending on the motivation, education, cultural background, etc., of the users. For example, pill failures generally range from 3% to 6% and condom failures from 5% to 15%.
31 Contraceptive Failure (Continued) Because of the need for extended periods of contraceptive use(i.e. 10 years or more), women using contraceptives of relativelyhigh effectiveness (<90%) will actually have a high risk of anunintended pregnancy in their reproductive lifetime.This is because the probability of remaining non-pregnant (P)for (n) years with a contraceptive of effectiveness (e) is anexponential function: Pn = en.
32 Contraceptive Failure (Continued) Example: Pn = en.where: n = 10 yearsContraceptiveEffectiveness (e)PnProbability of pregnancy (%)in 10 years = 1 – Pn.220.127.116.11.35.2033%65%80%
33 Couple Years of Protection (CYP) Question – how can one “add up” all of the different types of contraceptive services provided by various service delivery points to get a comparable indicator of performance?Answer – Use the measure of CYP.Definition – CYP is “a composite person-time measure of the total amount of protection conferred by all methods to all acceptors practicing for any length of time.”
34 Standard Values of Units Per CYP METHODOral contraceptivesCuT 380-A IUDNorplant (implant)Depo-Provera (inject.)Noristerat (inject.)SterilizationCondomsUNITS PER CYP15 cycles per CYP3.5 CYP per IUD3.5 CYP per implant4 doses per CYP6 doses per CYP10 CYP per procedure150 condoms per CYP