Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study
Abstract Background The causal relationship between maternal smoking in pregnancy and reduced offspring birth weight is well established and is likely due to impaired placental function. However, observational studies have given conflicting results on the association between smoking and placental we...
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| Format: | Article |
| Language: | English |
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BMC
2024-04-01
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| Series: | BMC Pregnancy and Childbirth |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s12884-024-06431-0 |
| _version_ | 1797219533353648128 |
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| author | Annika Jaitner Marc Vaudel Krasimira Tsaneva-Atanasova Pål R. Njølstad Bo Jacobsson Jack Bowden Stefan Johansson Rachel M. Freathy |
| author_facet | Annika Jaitner Marc Vaudel Krasimira Tsaneva-Atanasova Pål R. Njølstad Bo Jacobsson Jack Bowden Stefan Johansson Rachel M. Freathy |
| author_sort | Annika Jaitner |
| collection | DOAJ |
| description | Abstract Background The causal relationship between maternal smoking in pregnancy and reduced offspring birth weight is well established and is likely due to impaired placental function. However, observational studies have given conflicting results on the association between smoking and placental weight. We aimed to estimate the causal effect of newly pregnant mothers quitting smoking on their placental weight at the time of delivery. Methods We used one-sample Mendelian randomization, drawing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (N = 690 to 804) and the Norwegian Mother, Father and Child Cohort Study (MoBa) (N = 4267 to 4606). The sample size depends on the smoking definition used for different analyses. The analysis was performed in pre-pregnancy smokers only, due to the specific role of the single-nucleotide polymorphism (SNP) rs1051730 (CHRNA5 – CHRNA3 – CHRNB4) in affecting smoking cessation but not initiation. Results Fixed effect meta-analysis showed a 182 g [95%CI: 29,335] higher placental weight for pre-pregnancy smoking mothers who continued smoking at the beginning of pregnancy, compared with those who stopped smoking. Using the number of cigarettes smoked per day in the first trimester as the exposure, the causal effect on placental weight was 11 g [95%CI: 1,21] per cigarette per day. Similarly, smoking at the end of pregnancy was causally associated with higher placental weight. Using the residuals of birth weight regressed on placental weight as the outcome, we showed evidence of lower offspring birth weight relative to the placental weight, both for continuing smoking at the start of pregnancy as well as continuing smoking throughout pregnancy (change in z-score birth weight adjusted for z-score placental weight: -0.8 [95%CI: -1.6,-0.1]). Conclusion Our results suggest that continued smoking during pregnancy causes higher placental weights. |
| first_indexed | 2024-04-24T12:35:09Z |
| format | Article |
| id | doaj.art-75fa5f86c00e476699056822b4cb5928 |
| institution | Directory Open Access Journal |
| issn | 1471-2393 |
| language | English |
| last_indexed | 2024-04-24T12:35:09Z |
| publishDate | 2024-04-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Pregnancy and Childbirth |
| spelling | doaj.art-75fa5f86c00e476699056822b4cb59282024-04-07T11:33:38ZengBMCBMC Pregnancy and Childbirth1471-23932024-04-0124111210.1186/s12884-024-06431-0Smoking during pregnancy and its effect on placental weight: a Mendelian randomization studyAnnika Jaitner0Marc Vaudel1Krasimira Tsaneva-Atanasova2Pål R. Njølstad3Bo Jacobsson4Jack Bowden5Stefan Johansson6Rachel M. Freathy7Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of ExeterMohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of BergenDepartment of Mathematics and Statistics, Faculty of Environment, Science and Economy, University of ExeterMohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of BergenDepartment of Genetics and Bioinformatics, Division of Health Data and Digitalization, Norwegian Institute of Public HealthDepartment of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of ExeterDepartment of Medical Genetics, Haukeland University HospitalDepartment of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of ExeterAbstract Background The causal relationship between maternal smoking in pregnancy and reduced offspring birth weight is well established and is likely due to impaired placental function. However, observational studies have given conflicting results on the association between smoking and placental weight. We aimed to estimate the causal effect of newly pregnant mothers quitting smoking on their placental weight at the time of delivery. Methods We used one-sample Mendelian randomization, drawing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (N = 690 to 804) and the Norwegian Mother, Father and Child Cohort Study (MoBa) (N = 4267 to 4606). The sample size depends on the smoking definition used for different analyses. The analysis was performed in pre-pregnancy smokers only, due to the specific role of the single-nucleotide polymorphism (SNP) rs1051730 (CHRNA5 – CHRNA3 – CHRNB4) in affecting smoking cessation but not initiation. Results Fixed effect meta-analysis showed a 182 g [95%CI: 29,335] higher placental weight for pre-pregnancy smoking mothers who continued smoking at the beginning of pregnancy, compared with those who stopped smoking. Using the number of cigarettes smoked per day in the first trimester as the exposure, the causal effect on placental weight was 11 g [95%CI: 1,21] per cigarette per day. Similarly, smoking at the end of pregnancy was causally associated with higher placental weight. Using the residuals of birth weight regressed on placental weight as the outcome, we showed evidence of lower offspring birth weight relative to the placental weight, both for continuing smoking at the start of pregnancy as well as continuing smoking throughout pregnancy (change in z-score birth weight adjusted for z-score placental weight: -0.8 [95%CI: -1.6,-0.1]). Conclusion Our results suggest that continued smoking during pregnancy causes higher placental weights.https://doi.org/10.1186/s12884-024-06431-0SmokingPlacental weightBirth weightMendelian randomizationALSPACMoBa |
| spellingShingle | Annika Jaitner Marc Vaudel Krasimira Tsaneva-Atanasova Pål R. Njølstad Bo Jacobsson Jack Bowden Stefan Johansson Rachel M. Freathy Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study BMC Pregnancy and Childbirth Smoking Placental weight Birth weight Mendelian randomization ALSPAC MoBa |
| title | Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study |
| title_full | Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study |
| title_fullStr | Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study |
| title_full_unstemmed | Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study |
| title_short | Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study |
| title_sort | smoking during pregnancy and its effect on placental weight a mendelian randomization study |
| topic | Smoking Placental weight Birth weight Mendelian randomization ALSPAC MoBa |
| url | https://doi.org/10.1186/s12884-024-06431-0 |
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