Author Author Author PH251 Date Is Father Absence Early in Life Associated with Age at Menarche?

Overview  Introduction  Methods  Results  Discussion

Research Question  Is father absence at age 5 associated with age at menarche in the California Child Health and Development Studies (CHDS) Cohort?

Background  Public Health Implications of Earlier Menarche:  Breast cancer, obesity, type II diabetes  Conduct & behavioral disorders  Substance Abuse  Depression & Eating Disorders  Teen Pregnancy

Background  Average age about 12 1/2  But wide variation  Variation depends on: Race/ethnicity Maternal Age at Menarche BMI Family Environment Early in Life Father Absence Sibling Composition

Father Absence Theories PPsychosocial Acceleration Theory CChemosignal (Phermone) Theories PPaternal Investment Theory EEnergetics Theories LLife History Theory

Hypotheses  Girls with father absence at age 5 will have earlier age at menarche.  Father absent girls with more siblings will have a later age at menarche than father absent girls with less siblings.

Review of the Literature  Several studies found association  Campbell & Udry (1995) did NOT find this effect at age 5 in CHDS cohort…WHY NOT?  Strange covariates in model?  Statistical models used?  Effect modification?

Overview  Introduction  Methods  Results  Discussion

Study Participants 20,754 pregnancies in the CHDS 3,587 live, female births with no congenital anomalies born between June 1960 and January participated in five year 1, nine to eleven, and adolescent examinations 748 provided information on father absence at age 5, age at menarche, and sibling composition at age 5

Exposure  Father absence at age 5:  Five Year 1 Examination  Based on maternal report  “Mother only” or “Mother + Stepfather”

Outcome  Age at menarche  Adolescent Examination  Self-reported  Years, not months

Covariates  Chosen a priori from the literature:  Race  Maternal age at menarche  Social class  BMI – mediator  Siblings (total #, older male, older female)  Confounders included in statistical model if their removal changed the coefficient on father absence by ≥ 10%

Statistical Analysis  Statistical Models  Linear regression  Logistic regression  Polytomous logistic regression  Cox proportional hazards regression  Effect Modification  Sibling composition  Race  Sensitivity Analysis

Overview  Introduction  Methods  Results  Discussion

Descriptive Statistics

Covariates Associated with Father Absence  Race  Maternal age at menarche  Social class  BMI  Total # of Siblings  Total # Older Brothers  Total # Older Sisters

Covariates Associated with Age at Menarche  Race  Maternal age at menarche  Social class  BMI  Total # of Siblings  Total # Older Brothers  Total # Older Sisters

Crude Association  No difference in mean age at menarche by exposure (P = 0.5)  Father absent girls: 12.6  Father present girls: 12.7

Multivariate Model Results  Dichotomous Logistic Regression:  OR=1.4 (0.6, 2.9)  Polychotomous Logistic Regression:  OR=1.3 (0.6, 2.8) (Early vs. Normal)  OR=0.9 (0.4, 1.9) (Late vs. Normal)  Multivariate Linear Regression:  β =-0.2 (-0.5, 0.2)  Cox Proportional Hazard Regression:  HR=1.0 (0.4,1.8)

Interaction  Interaction terms tested using all our modeling approaches.  Father absence x number of siblings  Father absence x number of older sisters  Father absence x number of older brothers  Father absence x race  No evidence of interaction. All p-values > 0.5

Sensitivity Analysis  Recoded individuals living with “grandparents” and “other” as father absent.  Included individuals missing sibling information at age 5 and age  Used maternal age at menarche data from just the BASIC dataset and just the PNWORK dataset.

Overview  Introduction  Methods  Results  Discussion

Findings  Findings do not support father absence/sibling theories  Findings do not support most other literature  Findings DO support Campbell & Undry’s findings from 1995

Strengths  Sample size  Study Design  Statistical Methods  Multiple Multivariate Regression Models  Covariates Considered  Interactions Considered  Sensitivity Analyses

Limitations  Recall Bias  Father Absence Variable  Small n  Time of father absence unknown  Stepfather presence not considered  Pubertal Timing Indicator  SES Variable  Quality of Family Relationships

Future Research MEASURE STRESS MEASURE PUBERTAL ONSET