Body composition, smoking, and spontaneous dizygotic twinning.
OBJECTIVE
To examine differences in body composition and smoking between mothers of spontaneous monozygotic and dizygotic twins, while taking into account maternal age, gravidity, and educational attainment.


METHODS
Retrospective cohort study.


METHODS
The Netherlands Twin Register.


METHODS
Mothers of twins (n = 19,357) registered with the Netherlands Twin Register. Data were selected from mothers of spontaneous monozygotic twins (MZ; n = 5663) and mothers of spontaneous dizygotic twins (DZ; n = 8515).


METHODS
None.


METHODS
The odds of having spontaneous DZ twins versus spontaneous MZ twins as a function of height, body mass index (BMI), and smoking before pregnancy, after accounting for age, gravidity, and educational attainment.


RESULTS
Compared with spontaneous MZ twinning, spontaneous DZ twinning is significantly associated with increasing height (odds ratio, 1.6; 95% confidence interval [CI], 1.5-1.8 for the tallest versus the shortest height quartile), an increased BMI (odds ratio, 1.3; 95% CI, 1.1-1.4 for overweight vs. normal weight), and smoking before the twin pregnancy (odds ratio, 1.4; 95% CI, 1.3-1.5 for smoker vs. nonsmoker). Maternal age and gravidity, but not educational attainment, had to be included in the model.


CONCLUSIONS
Spontaneous dizygotic twinning is associated with body composition and smoking.
Hoekstra
Chantal
C
Department of Biological Psychology, VU University Amsterdam, Amsterdam, The Netherlands.
Willemsen
Gonneke
G
van Beijsterveldt
C E M Toos
CE
Lambalk
Cornelius B
CB
Montgomery
Grant W
GW
Boomsma
Dorret I
DI
D000293:Adolescent; D000328:Adult; D001823:Body Composition; D004522:Educational Status; D005260:Female; D020073:Gravidity; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D015995:Prevalence; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult