Cohort analysis of adolescent first birth timing and births progression in West-Africa

Adebowale Ayo Stephen

, Bamgboye Eniola

, Adjiwanou Visseho

1Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, Ibadan, Nigeria

2Visiting Academic Centre for Actuarial Research (CARe), Faculty of Commerce, University of Cape Town, Cape Town, South Africa

3Centre for Actuarial Research (CARe), Faculty of Commerce, University of Cape Town, Cape Town, South Africa

Email: Adehamilt2008@yahoo.com

α

Eshetu and Dula, 2014;

Mturi, 2015

;

Age at first birth

= {x = 1, if age at first birth is less than 20 years x = 0, if age at first birth is 20 − 49 years

𝑦_𝑡

𝜁₀ and 𝜁₁

𝑦_𝑡 = 𝜁₀+ 𝜁₁𝑥 + 𝜀_𝑖 (1)

𝜁₁= 𝑟_𝑡 =𝑑 (𝑛_𝑐 𝑁_𝑐)

𝑑𝑡 (2) ε

𝑆(𝑡_(𝑗−1)) = ∏^𝑗−1𝑃 (𝑇 > 𝑡_(𝑖)⧹𝑇 ≥ 𝑡_(𝑖)) (3)

𝑖−1

𝑙𝑜𝑔{ℎ_𝑖(𝑡) ℎ⁄ ₀(𝑡)}

= 𝛽₁𝑥_1𝑖+ 𝛽₂𝑥_2𝑖+ ⋯ + 𝛽_𝜂𝑥_𝜂𝑖 (4) β₁, β₂, … , β_η

β

𝑡₍₁₎, 𝑡₍₂₎, … , 𝑡_(𝑘) 𝑡_(𝑖)

𝑝 = 𝑒𝑥𝑝 {∑^𝜂_𝑗=1𝛽_𝑗𝑋_𝑗𝑖}

∑_{𝐼∈𝑅(𝑡(𝑖)}𝑒𝑥𝑝 {∑^𝜂_𝑗=1𝛽_𝑗𝑋_𝑗𝑖} (5)

𝐿(𝛽) = ∏ [ 𝑒𝑥𝑝 {∑^𝜂_𝑗=1𝛽_𝑗𝑋_𝑗𝑖}

∑_{𝐼∈𝑅(𝑡(𝑖)}𝑒𝑥𝑝 {∑^𝜂_𝑗=1𝛽_𝑗𝑋_𝑗𝑖}] (6)

𝑘 𝑖=1

𝐿𝐿(𝛽)

= ∑ ∑ 𝛽_𝑗𝑋_𝑗𝑖

𝜂

𝑗=1 𝑘

𝑖=1

− ∑ 𝑙𝑜𝑔_𝑒

𝑘

𝑖=1

[ ∑ 𝑒𝑥𝑝 {∑ 𝛽_𝑗𝑋_𝑗𝑖

𝜂

𝑗=1

}

𝐼∈𝑅(𝑡_(𝑖)

] (7)

β

𝒓_𝒕 ρ

0 20 40 60 80 100 120

1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994

Proportion

Women's birth cohort

Nigeria Ghana Gambia Liberia

0 0.2 0.4 0.6 0.8 1 1.2

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Probability

Date at first birth

Nigeria Ghana Gambia Liberia

𝑥̅ ± 𝜎 𝑥̅ ± 𝜎 𝑥̅ ± 𝜎 𝑥̅ ± 𝜎 𝑥̅ ± 𝜎 𝑥̅ ± 𝜎 𝑥̅ ± 𝜎 𝑥̅ ± 𝜎

𝑥̅

𝒙̅

≥ 0

0.01 0.02 0.03 0.04 0.05 0.06

2 3 4 5 6 7 8 9 10

Birth Progression Rate

Parity

<20 20+

0 0.01 0.02 0.03 0.04 0.05

2 3 4 5 6 7 8 9 10

Birth Progression Rate

Parity

<20 20+

0 0.01 0.02 0.03 0.04 0.05 0.06

2 3 4 5 6 7 8 9 10

Birth Progression Rate

Parity

<20 20+

0 0.01 0.02 0.03 0.04 0.05 0.06

2 3 4 5 6 7 8 9 10

Birth Progression Rate

Parity

<20 20+

0 0.01 0.02 0.03 0.04 0.05 0.06

2 3 4 5 6 7 8 9 10

Birth Progression Rate

Parity

Nigeria Ghana

Gambia Liberia

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04

2 3 4 5 6 7 8 9 10

Birth Progression Rate

Parity

Nigeria Ghana

Gambia Liberia

Eshetu Gurmu, Dula Etana. 2014. Age at First Marriage and First Birth Interval in Ethiopia:

Analysis of the Roles of Social and Demographic Factors. African Population Studies. Vol. 28(3):1332-1344.

Mturi Akim J. 2015. Predisposing factors and consequences of childbearing among young unmarried women in North West, South Africa. African Population Studies. Vol. 29(2):

1954-1971.

evision of World Population Prospects