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Many more unintended pregnancies
- Douwe A Verkuyl (16 February 2009)
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Maternal Smoking in Pregnancy as a risk factor for Small for Gestational Age (SGA) Births
- Susan M O'Connell, Elaine O'Mullane, Joan P Murphy, Edna F. Roche, Margaret Sheridan, and Hilary M.C.V. Hoey. (26 February 2009)
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Preconceptionally self-reported use and intention to use of folic acid -supplements
- Lolkje TW de Jong-van den Berg, Denhard J de Smit, Willemijn M Meijer (7 April 2009)
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Douwe A Verkuyl, obstetrician Stadskanaal Hospital
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Quoting from the paper : "Among the women who became pregnant within three months, 23% answered no at interview when asked if they intended to become pregnant within the next 12 months. This proportion is lower than the true unplanned pregnancy rate, as many of those women we have classified as planning a pregnancy may not have planned to become pregnant within the three month time window, and so, according to definitions used in other studies, their pregnancy would have been unplanned." and "[When] the women became pregnant they attended Southampton’s Princess Anne Maternity Hospital for fetal ultrasonography at 11, 19, and 34 weeks’ gestation. We collected data on menstruation and ultrasonography from the women early in pregnancy" There is a risk of a misunderstanding here. It appears that from the pregnancies somewhat more than 23% was unintended. However, the unwanted (and mostly unintended) pregnancies never came to the attention of the maternity hospital presumably nor the spontaneous abortions. The true unplanned pregnancy rate will be nearer 50% of all the pregnancies having occurred in 3 months in the 12445 women. Perhaps the "unplanned pregnancy rate" should be called ratio with in the denominator ongoing pregnancies. Competing interests: None declared |
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Susan M O'Connell, Lecturer in Paediatrics Department of Paediatrics, University of Dublin, Trinity College, Ireland, Elaine O'Mullane, Joan P Murphy, Edna F. Roche, Margaret Sheridan, and Hilary M.C.V. Hoey.
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I refer with interest to your recent BMJ paper "Women's compliance with nutrition and lifestyle recommendations before pregnancy: general population cohort study" by Inskip et al in the Research section and also to a previous paper in the Views & Reviews section on the importance of accurate data on maternal smoking in pregnancy 1. Our recent study on risk factors associated with being born small for gestational age (SGA) in a two year cohort of births from mid-1999 to mid-2001 in a large Dublin maternity hospital has identified alarming rates of maternal smoking during pregnancy. SGA was defined as birthweight ≤ -2SDS. Of all the modifiable factors identified as risks for SGA, the strongest case can be made for endeavouring to decrease smoking amongst pregnant women, ideally by targeting smoking women before they become pregnant 2 The association of smoking with a reduction in birthweight has been well established 3. A number of studies have demonstrated an association between maternal smoking and lower birth weights with estimates of the reduction ranging from 100 to 300g 4 5 6 7. The effect of maternal smoking on low birthweight seems to be attributable to intrauterine growth restriction (OR 2.07) rather than to preterm delivery 4. Looking at the causal impact of late-term (8th month of gestation) maternal smoking on birthweight, on average smokers have been found to give birth to infants weighing 348g less than those of non-smokers 8. A dose-response relationship has been demonstrated with the degree of impaired fetal growth and with the average weight deficit of 458g in infants born to heavy smokers. In addition, passive smoke exposure during pregnancy plays a role and can result in an average weight deficit of 192g 4 9. However, some authors have argued that the effects of smoking are confounded by lifestyle and physiological factors associated with both maternal smoking and birthweight 10 11. The effect of exposure to cigarette smoking during pregnancy has also been shown to be modified adversely by advancing maternal age in an American study by Fox et al., although number of cigarettes per day and years of smoking were not examined 12. It is hypothesised that the aetiology of the observed impairment in fetal growth is due to a combination of carbon monoxide exposure (decreased fetal haemoglobin oxygen-carrying capacity) and nicotine (inducing release of maternal catecholamines). This results in repetitive episodes of reduced maternal perfusion of the placenta. Using a definition for SGA of birth weight less than the gender specific 10th percentile for gestational age at birth (in term infants >37 weeks), in the Auckland Birthweight Collaborative Study the population attributable fraction for smoking suggested that up to 18% of SGA infants born could be related to maternal smoking 13.Overall there was a 25.8% rate of maternal smoking in pregnancy in our study cohort. This compares with rates of smoking found in similar studies (26.2%) 4 (30%) 14, however a lower rate (11%) has recently been reported in the USA 15. Overall rates of smoking for women (irrespective of pregnancy status) in the 18-34 year age group reported by the Irish Central Statistics Office were 40% and 33% for 1998 and 2002 respectively 16. There was a significant difference found in our study in the percentage of mothers of SGA infants who smoked during pregnancy compared with mothers in the non-SGA group. Overall 55% of mothers of infants born SGA smoked in pregnancy versus 25.7% of the mothers in the non-SGA group (number of cigarettes ranged from occasional to > 20 cigarettes per day). Similarly, a recent Irish study of the association between maternal characteristics and birth weight in 1048 live infants has shown a clear birthweight gradient in relation to maternal smoking, from 38% of mothers of infants in the lowest quintile for birth weight having smoked, versus 11.4% of mothers of infants in the highest 17. These findings while concerning are not surprising as cigarette smoking during pregnancy is the single most common cause of impaired fetal growth 14 and is also one of the most important avoidable factors associated with low birth weight 4. In comparison with a specific study of rates of maternal smoking in groups of SGA infants compared with appropriate for gestational age (AGA) infants (25% versus 17%) 18 the rate of maternal smoking in the SGA group in our study appears very high. However, in Doctor et al's study, SGA was defined as birth weight < 10th centile where as we defined SGA birthweight ≤ -2SDS using appropriate references . The number of cigarettes smoked also appears to be important. For example, McDonald et al found that smoking more than 20 cigarettes per day was associated with a more than threefold increased risk of delivering an infant with a birth weight <5th centile 19. Similar results have been found in our study with 4% of mothers of SGA infants smoking more than 20 cigarettes per day versus 0.7% in the non-SGA group. The economic costs of smoking in relation to low birth weights are substantial and as it is one of the most preventable factors associated with SGA births, it raises clear public health issues in this country. With intensive anti-smoking assistance to pregnant women, studies have shown that some fetal growth retardation can be overcome 20. Even women who stop smoking in the first trimester of pregnancy may have a risk of IUGR similar to that of non- smokers 4. However, other risk factors interact with smoking during pregnancy; it has been shown only to have half the impact on fetal growth in obese versus thin mothers, and in black versus white mothers 5, and this is clearly just one of the contributory risk factors for SGA, which interacts with social deprivation, maternal education and diet during pregnancy. In addition, implementation of best practice to promote prenatal smoking cessation is shown to be limited due to resource and organisational issues 21. Although Ireland has led the way in Europe with the introduction of the law banning tobacco use in the workplace in March 2004 22, 23 24 smoking rates of young people in Ireland remain high (16% of 12-17 year olds) 25. The vast majority of smokers start smoking by age 17, but young women are more likely to start smoking later than young men, but are also more likely to continue smoking later in life. A study by the Office of Tobacco Control has reported that 25% of women who commence smoking do so after age 17 years 26. Hence advertising campaigns to de-glamourise smoking, targeted specifically at teenage girls, such as the "NICO" campaign, developed in 2000 27, are well founded. The effects of maternal smoking during pregnancy are not sufficiently highlighted to this younger age group and this is an area that requires further development of specific campaigns. In addition, as smoking during pregnancy is associated with many later post-natal problems such as lower rates of childhood immunisation 28, decreased lung function 29 and sudden infant death syndrome (SIDS) 30 31, women need to be made aware of its long-term implications. However the message is not being adequately conveyed. For example, since the "Back to Sleep" intervention campaign initiated in the UK in 1991 and a 75% overall drop in the incidence of SIDS 32, the pooled risk associated with maternal smoking during pregnancy has risen to almost four-fold 33. In October 2007 a leading research team in the UK concluded that maternal smoking during pregnancy -- already a recognised factor in 90% of cases of SIDS -- met the criteria for causality and was directly responsible for 60% of such deaths 30 34. Put in a different context, up to 60% of cases of SIDS can be avoided by eliminating smoking during pregnancy 35. Clearly the message on smoking in pregnancy seems to have achieved less effect than the message on sleeping position 31.Hence, as stated by O'Gorman 1 tackling social disadvantage is a huge challenge which has far-reaching implications in the area of smoking prevention. In addition, the finding by Inskip et al, that those women who became pregnant within three months of the study interview were not statistically less likely to be smoking than those who did not become pregnant, is a further indication that the message on the harmful effects of smoking during pregnancy is not getting across to women of reproductive age. As smoking is a notoriously addictive agent, and a substantial proportion of pregnancies are unplanned, it behoves us to promote public health campaigns specifically aimed at both smoking prevention and smoking cessation in women and young girls well before pregnancy occurs. REFERENCES: 1. O'Gorman C. We need better data on smoking in pregnancy. Bmj 2008;336(7639):330. 2. O'Connell SM OCA, O'Mullane E, Hoey HMCV. Medical, nutritional and dental considerations in children with low birth weight. Pediatr Dent In press 2009. 3. Kramer MS. Determinants of low birth weight: methodological assessment and meta-analysis. Bull World Health Organ 1987;65(5):663-737. 4. Horta BL, Victora CG, Menezes AM, Halpern R, Barros FC. Low birthweight, preterm births and intrauterine growth retardation in relation to maternal smoking. Paediatr Perinat Epidemiol 1997;11(2):140- 51. 5. Cliver SP, Goldenberg RL, Cutter GR, Hoffman HJ, Davis RO, Nelson KG. The effect of cigarette smoking on neonatal anthropometric measurements. Obstet Gynecol 1995;85(4):625-30. 6. Macmahon B, Alpert M, Salber EJ. Infant weight and parental smoking habits. Am J Epidemiol 1965;82(3):247-61. 7. Meyer MB, Comstock GW. Maternal cigarette smoking and perinatal mortality. Am J Epidemiol 1972;96(1):1-10. 8. Hamilton BH. Estimating treatment effects in randomized clinical trials with non-compliance: the impact of maternal smoking on birthweight. Health Econ 2001;10(5):399-410. 9. Roquer JM, Figueras J, Botet F, Jimenez R. Influence on fetal growth of exposure to tobacco smoke during pregnancy. Acta Paediatr 1995;84(2):118- 21. 10. Yerushalmy J. The relationship of parents' cigarette smoking to outcome of pregnancy--implications as to the problem of inferring causation from observed associations. Am J Epidemiol 1971;93(6):443-56. 11. Hickey RJ, Clelland RC, Bowers EJ. Maternal smoking, birth weight, infant death, and the self-selection problem. Am J Obstet Gynecol 1978;131(7):805-11. 12. Fox SH, Koepsell TD, Daling JR. Birth weight and smoking during pregnancy--effect modification by maternal age. Am J Epidemiol 1994;139(10):1008-15. 13. Thompson JM, Clark PM, Robinson E, Becroft DM, Pattison NS, Glavish N, et al. Risk factors for small-for-gestational-age babies: The Auckland Birthweight Collaborative Study. J Paediatr Child Health 2001;37(4):369- 75. 14. Kramer MS. Socioeconomic determinants of intrauterine growth retardation. Eur J Clin Nutr 1998;52 Suppl 1:S29-32; discussion S32-3. 15. Martin JA, Kochanek KD, Strobino DM, Guyer B, MacDorman MF. Annual summary of vital statistics--2003. Pediatrics 2005;115(3):619-34. 16. Central Statistics Office. Prevalence of cigarette smoking by sex and age. http://www.cso.ie/releasespublications/documents/other_releases/2003/health.pdf 2003:8. 17. Murrin C, Segonds-Pichon A, Fallon UB, Hannon F, Bury G, Loftus BG, et al. Self-reported pre-pregnancy maternal body mass index and infant birth- weight. Ir Med J 2007;100(8):suppl 20-3. 18. Doctor BA, O'Riordan MA, Kirchner HL, Shah D, Hack M. Perinatal correlates and neonatal outcomes of small for gestational age infants born at term gestation. Am J Obstet Gynecol 2001;185(3):652-9. 19. McDonald AD, Armstrong BG, Sloan M. Cigarette, alcohol, and coffee consumption and prematurity. Am J Public Health 1992;82(1):87-90. 20. Sexton M, Hebel JR. A clinical trial of change in maternal smoking and its effect on birth weight. Jama 1984;251(7):911-5. 21. Hartmann KE, Wechter ME, Payne P, Salisbury K, Jackson RD, Melvin CL. Best practice smoking cessation intervention and resource needs of prenatal care providers. Obstet Gynecol 2007;110(4):765-70. 22. McElvaney NG. Smoking ban--made in Ireland, for home use and for export. N Engl J Med 2004;350(22):2231-3. 23. The Lancet E. Ireland's smoking ban is an admirable achievement. Lancet 2005;365(9467):1282. 24. Spinney L. Public smoking bans show signs of success in Europe. Lancet 2007;369(9572):1507-8. 25. Office for Tobacco Control. Children, Youth and Tobacco: Behaviour, Perceptions and Public Attitudes. 2006. 26. Office for Tobacco Control. Irish Women and Tobacco: Knowledge, Attitudes and Beliefs - Research Report on Tobacco Use in Ireland. http://www.otc.ie/uploads/Publications%20- %20Irish%20Women%20and%20Tobacco%20low%20res%20version.pdf 2003. 27. Institute of Advertising Practitioners in Ireland. NICO - Deglamourisation of smoking. http://www.iapi.ie/adfx/cases/cases04/nico.htm 2004. 28. Pearce A, Law C, Elliman D, Cole TJ, Bedford H. Factors associated with uptake of measles, mumps, and rubella vaccine (MMR) and use of single antigen vaccines in a contemporary UK cohort: prospective cohort study. Bmj 2008;336(7647):754-7. 29. Tager IB, Ngo L, Hanrahan JP. Maternal smoking during pregnancy. Effects on lung function during the first 18 months of life. Am J Respir Crit Care Med 1995;152(3):977-83. 30. Gornall J. Does cot death still exist? Bmj 2008;336(7639):302-4. 31. Fleming P, Blair PS. Sudden Infant Death Syndrome and parental smoking. Early Hum Dev 2007;83(11):721-5. 32. Blair PS, Sidebotham P, Berry PJ, Evans M, Fleming PJ. Major epidemiological changes in sudden infant death syndrome: a 20-year population-based study in the UK. Lancet 2006;367(9507):314-9. 33. Mitchell EA, Milerad J. Smoking and the sudden infant death syndrome. Rev Environ Health 2006;21(2):81-103. 34. Gornall J. Protection for the innocent. Bmj 2007;334(7603):1083-5. 35. Foundation for the Study of Infant Deaths. Smoking and sudden infant death syndrome. www.fsid.org.uk/smoking-fleming-press.html 2007. Competing interests: None declared |
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Lolkje TW de Jong-van den Berg, Professor in pharmacoepidemiology Antonius Deusinglaan 1 9713 AV Groningen, Denhard J de Smit, Willemijn M Meijer
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Inskip st al (!) showed in their study that few women change their health behaviour before pregnancy, including the use of folic acid. In this respect we will present a study from the Netherlands evaluating the use of folic acid before conception related to the ‘time to pregnancy’ expected (TTP-expected)
Periconceptional folic acid use decreases the risk of neural tube defects and other birth defects. Since folic acid fortified foods are not mandatory in the Netherlands, women trying to conceive are recommended to use supplements starting at before conception since 1994. Preconceptional care is not structural in the Netherlands which makes, it difficult to reach the women in time. However, the rate of planned pregnancies is high, about 85-90%. Therefore use of supplements can easily be planned as well, provided that women are in time aware of the necessity to start folic acid use before conception. Data about self-reported FA-use was obtained from a study evaluating in a controlled intervention-reference design the effects of an educational intervention in the community pharmacy (2) on the knowledge about FA and the use of FA-supplements. Our findings show a completely different picture from that reported by Inskip et al. (1). Data were collected at T0 of our design through 23 community pharmacies all of whom had not implemented FA-education interventions before. Random samples of women aged 25-35 that had used oral contraceptives at least one time in the 12 months before T0 were drawn. A sample of 140 women (or smaller if the study population in a pharmacy was less than 280) per pharmacy was drawn. A validated questionnaire was used to collect data with respect to the variables FA-knowledge and consumption (3). Questions about TTP-expected were added. At T0 2821 questionnaires were sent of which 1965 (70%) were returned and 1838 (65%) were eligible for analysis. The table shows the distribution of self-reported FA-supplement use and intention to use FA related to respondents‘ time to pregnancy expected. The data show higher percentages of use and intention to use when the TTP-expected is shorter. Table . Use or intention to use of folic acid supplements in young women related to ‘time to pregnancy expected’ (TTP-expected).
We would like to add the following comments on these findings. Firstly, in this group the reported FA-supplement use among pregnant women is relatively high compared with the overall pattern in the Netherlands and can be explained by the characteristics of the study population (age, former OC-use). A recent study have however confirmed that OC-use is the strongest predictor of FA-supplement use now. (3) Secondly, although the overall FA-consumption pattern in the Netherlands is lower than in our studygroup, FA-supplement consumption in the Netherlands is much higher than in other countries and has contributed to a decline of NTD birth prevalence (4). This is probably partly due to longstanding and sustained educational interventions in the Netherlands as compared to other countries. Thirdly, our data (not shown here) also reveal strong relations between correct knowledge about FA and TTP-expected. This is in line with the understanding that people are more open to information that applies to their actual situation or expectations and thus emphasizes the need to try and inform women in the right time-window. Finally, preliminary analysis of the data collected at T1 show the same pattern as the data reported here. In conclusion, our data collected in the preconception time window show that relevant levels of adequate periconceptional FA-consumption are achievable and this contradicts the conclusions of Inskip et al. Interventions implemented in structural health care setting like the community pharmacy contribute to the use of FA before pregnancy. 1. Hazel M Inskip, , Sarah R Crozier, Keith M Godfrey, Sharon E Borland, Cyrus Cooper. Southampton Women’s Survey Study Group. Women’s compliance with nutrition and lifestyle recommendations before pregnancy: general population cohort study. BMJ 2009;338;b481 doi:10.1136/bmj.b481 2. Meijer WM, De Smit DJ, Jurgens RA, De Jong-van den Berg LTW (2004) Pharmacists’ role in improving awareness about folic acid: a pilot study on the process of introducing an intervention in pharmacy practice. Int J Pharm Pract 12: 29-35. 3. de Walle HE,.de Jong-van den Berg LT. Ten years after the Dutch public health campaign on folic acid: the continuing challenge. Eur J Clin Pharmacol. 2008;64:539-43. 4. Busby A, Abramsky L, Dolk H, Armstrong B, Eurocat Folic Acid Working Group. Preventing neural tube defects in Europe: population based study. BMJ 2005;330:574-5. Competing interests: None declared |
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