smoking during pregnancyRestriction of fetal growth is one known complication of smoking during pregnancy. Researchers know the connection exists, but little is known about when the growth restriction starts and how it progresses. Researchers used data collected for the IINMA Mother and Child Cohort to evaluate when fetal growth restriction starts and the growth areas affected the most/least.

Medical information from nearly 2,500 births was evaluated for the study. Information was collected between 2003 and 2008. Measurements were noted for weeks 12, 20 and 34 of gestation for fetal weight, abdominal circumference, femur length and diameter. Maternal data regarding smoking habit was collected via questionnaire, but blood samples were also tested for cotinine to verify the answers. Cotinine is found in tobacco with traces being left behind as a biomarker in blood.

Results: Smoking during pregnancy affected femur length the most – with an average length restriction of 9.4%. Abdominal circumference was also affected, but not as much as femur length. Quitting smoking before the 12th week of pregnancy may prevent fetal growth restriction on some levels, but femur length remained affected even if the mother stopped smoking.

Source: Iñiguez C, Ballester F, Costa O, Murcia M, Souto A, Santa-Marina L, Aurrekoetxea JJ, Espada M, Vrijheid M, Alvarez-Avellón SM, Alvarez-Pedrerol M, Rebagliato M. Maternal Smoking During Pregnancy and Fetal Biometry: The INMA Mother and Child Cohort Study. Am J Epidemiol. 2013 Sep 5.