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Maternal smoking and blood pressure in 7.5 to 8 year old offspring
R Morley1, C Leeson Payne, G Lister
1MRC Dunn Nutrition Unit, Cambridge.
Insights
Maternal smoking during pregnancy affects children's future blood pressure differently based on gestational age. Babies born preterm had lower blood pressure, while those born at term had higher blood pressure, indicating gestation-dependent programming.
Area of Science:
- Developmental origins of health and disease
- Perinatal programming
- Cardiovascular health
Background:
- Reduced fetal growth is linked to later blood pressure variations.
- Maternal smoking is associated with reduced fetal growth.
- Gestational age may influence the programming of blood pressure.
Purpose of the Study:
- To investigate if maternal smoking in pregnancy programs later blood pressure differently based on gestational age.
- To examine the long-term blood pressure consequences of maternal smoking in preterm and term infants.
Main Methods:
- Prospective study of 618 children aged 7.5–8 years born preterm.
- Analysis of systolic and diastolic blood pressure in children based on maternal smoking status and gestational age.
- Statistical adjustment for confounding factors like social class and current weight.
Main Results:
- Children of mothers who smoked had significantly lower systolic blood pressure if born before 33 weeks' gestation.
- Children of mothers who smoked had significantly higher systolic blood pressure if born at 33 or more weeks' gestation.
- Each 10 cigarettes/day increase was associated with a 1.5 mm Hg fall (pre-33 weeks) and 2.9 mm Hg rise (≥33 weeks) in systolic pressure.
Conclusions:
- Maternal smoking during pregnancy has long-term, gestation-dependent effects on children's blood pressure.
- Fetal growth insults programmed by maternal smoking have consequences for later cardiovascular health.
- This study provides evidence for the differential programming of blood pressure by maternal smoking based on length of gestation.
Abstract:
Reduced fetal growth in babies born preterm may be associated with reduced later blood pressure, but in children born at term, higher blood pressure. It was hypothesised, therefore, that maternal smoking in pregnancy, associated with reduced fetal growth, programmes later blood pressure differentially according to length of gestation. Six hundred and eighteen children born preterm and now aged 7.5 to 8 years were studied prospectively. Systolic blood pressure in children from smoking compared with non-smoking mothers was significantly lower in those born before 33 weeks' gestation and significantly higher in those born at 33 or more weeks. Within the range 0-40 cigarettes per day until delivery (after adjusting for potentially confounding factors, including social class and current weight) each 10 was associated with a 1.5 mm Hg fall and 2.9 mm Hg rise in pressure for children born below or above 33 weeks' gestation respectively. Similar though smaller differences were seen in diastolic pressure. These data support our hypothesis that later effects of insults impairing fetal growth are gestation dependent, and provide the first evidence that maternal smoking may have long term consequences for blood pressure in children.