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Smoking is Associated with Delayed Embryonic Development

ACCORDING to a study conducted by Erasmus MC, University Medical Centre, Rotterdam, The Netherlands, females who smoked during the period of conception, either before or after, presented with a delay in the development of the embryo. The delayed development of the embryo in female smokers showed smaller foetuses at the 20-week ultrasound scan, and lower birth weights.

The large prospective study conducted at the Department of Obstetrics and Gynaecology, observed 689 females with single pregnancies from 2010—2018. The researchers discovered that by the 10th week, the development of the embryo in participating females smoking 10 or more cigarettes a day was delayed by a day compared to the non-smokers. Additionally, in females who smoked and had achieved pregnancy either through in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI), the embryonic developments were delayed by 1.6 days. According to the results, it was also unlikely that the embryos of smoking females were able to catch up with the non-smoking participants over the course of the pregnancy. Furthermore, the babies from the smoking group were born smaller for their gestational age, and weighed approximately 93 grams less than babies born to non-smoking females.

The researchers used a virtual reality technology to investigate the embryos’ development morphology, and compared it against Carnegie Stages, which covers the established stages of embryonic development. The study’s strengths were the reliable dates of conception in the substantial number of pregnancies studied, especially within the IVF and ICSI couples, and the accessibility of the ultrasound data. However, one of the limitations was the fact that a questionnaire was used for all females involved in the study, including those with IVF and ICSI pregnancies, to confirm smoking habits, which could be somewhat inaccurate.

Melek Rousian, Gynaecologist at Erasmus MC, who led the study, said: “The results of this study emphasise the importance of smoking cessation prior to conception and that efforts to help women stop smoking should focus on this time window. If possible, women should stop smoking from the very moment they plan to become pregnant, but it’s always a good thing to stop smoking anyway, particularly at any stage of pregnancy. Smoking not only impacts an embryo’s growth during pregnancy and birth weight, but also embryo development right from the very early stages of pregnancy.”