Effects of Maternal Smoking during Pregnancy on the Weight of Infant - Research Paper Example

Relationship between maternal smoking during pregnancy and infant birth weight Insert Name Instructor’s Name Date Effects of Maternal smoking during pregnancy on the weight of infant Introduction Numerous studies have been conducted to explore the relationship between maternal smoking during pregnancy and low infant weight. Maternal smoking during pregnancy has been associated with several unfavorable outcomes that include; low birth weight, increased morbidity and mortality rates as well as premature birth. According to a study conducted by chiolero et el. 2005, Maternal smoking during pregnancy resulted in low birth weight, and premature birth. The study established that there is a strong association between the number of cigarettes smoked and the low birth weight. The study also established that the birth weights of infants whose mothers quit smoking during pregnancy was significantly higher than the birth weight of infants whose mothers continued smoking. A similar study was conducted by wahabi et al. 2013, to evaluate the effect of exposure to tobacco smoke on mothers during pregnancy on infant weight. The findings of the study indicate that the average birth weight of infants whose mothers were exposed to tobacco smoke had a weight that was significantly less by 35g as compared to that of mothers who were not exposed to tobacco smoke. Studies have confirmed that exposure to tobacco smoke is associated with impaired fetal growth. Another study was carried out to evaluate the difference between exposure to environmental tobacco smoke and the antenatal maternal smoking on the infant birth weight. The findings of the study indicate that exposure to antenatal tobacco smoke led to a significantly higher birth weight as compared to exposure to environmental tobacco smoke. The objective of the analysis was to evaluate the relationship between dose of tobacco smoke and the response in birth weight of the infant (Ward, Lewis, & Coleman, 2007). Most of the relationships explored above were successful in indicating the relationship between tobacco smoke exposure and low infant weight. However, the analysis failed to evaluate the other factors that have been established to contribute to difference in birth weight. These factors include genetic predisposition, maternal weight and socioeconomic status. The socioeconomic status of the mother has been established to contribute to the birth weight of infant because of the ability of the mother to access nutritionally adequate foods that will lead to sustained weight. Additionally, similar analysis should evaluate the effect of mother’s occupation on infant weight. The study established a gap in the existing knowledge on the relationship between infant birth weight and maternal smoking. Genetic predisposition, a factor that has been observed to be closely linked with the race of the mother has been observed to be the cause of differences in the birth weight of infants. Also, it is of interest to observe whether the effect of maternal smoking is the same across the different categories of race. The study will lead to an increase in the knowledge that exists on the effects of maternal exposure during pregnancy of tobacco smoke on the birth weight of infant. Data The data is made up of 189 respondents and the eleven variables as follows; identification code, low birth weight, age of the mother, weight in pounds at the last menstrual period, race, smoking status during pregnancy, history of premature labor, history of hypertension, presence of uterine irritability, number of physician visits during the first trimester, and the birth weight in grams. The variables of interest in this analysis are; birth weight, smoking status during pregnancy and race. Findings The summary statistics for the categorical and numeric variables used in the analysis are presented below. Race and smoking status are categorical variables and as such the frequencies will be presented. The frequencies for the variable race and smoking status during pregnancy are detailed below Race of Mother Frequency Percent Valid percent Cumulative percent white 96 50.8 50.8 50.8 valid black 26 13.8 13.8 64.6 other 67 35.4 35.4 100 total 189 100 100 The percentage of white respondents is large (over 50%) which indicates that there is a high probability that the proportions of the categorical variable race will not be significantly equal. However, the chi-square test of proportions will be used to evaluate if the proportions are significantly equal or not. Smoking status during pregnancy Frequency Percent Valid percent Cumulative percent No 115 60.8 60.8 60.8 valid Yes 74 39.2 39.2 100 Total 189 100 100 The percentage of respondents who do not smoke is large (over 60%) which indicates that there is a high chance that the proportions of the variable smoking status during pregnancy will not be significantly equal. Nonetheless, the chi-square test of proportions will be used to evaluate if the proportions are significantly equal or not. Descriptive statistics N Minimum Maximum Mean Standard Deviation Birth Weight 189 709 4990 2944.66 729.022 189 The mean birth weight is computed to be 2944.66 and the variable birth weight has a minimum value 709 and a maximum value 4990. The average birth weight is important because it will be used in the comparison of the low birth weight values. It is essential to identify the distribution of this random variable because all parametric tests we have to conduct require that the distribution should be randomly distributed. Histogram with normality plots will be used to gain an insight into the distribution of the variable birth weight. The histogram indicates that the distribution of the variable birth weight is fairly normal. Alternatively, normal P-P plots can be used to evaluate the most possible distribution of the variable birth weight. The normal P-P plots indicates that the distribution of the variable birth weight is fairly normal. The parametric alternative is used to confirm the distribution of the variable birth weight. The test is not significant and as such we fail to reject the null hypothesis that the distribution of the variable birth weight is significantly normal. Therefore, the distribution of the variable birth weight is assumed to be normal. The p-value computed from the test is 0.2 while the significance level is 0.05. Tests for normality Kolmogorov Smirnov Shaipiro wilk statistic df sig statistic df Sig Birth weight 0.043 189 0.2 0.992 189 0.438 Chi-Square tests Value df Sig Pearson Chi-square 21.779 2 0.00 Likelihood ratio 22.997 2 0.00 Linear-by-Linear 21.609 1 0.00 N 189 The chi square test is used to evaluate of there is a significant difference in the proportions of the categorical variables used in the study. Test Statistic Smoking Status During Pregnancy Chi-Square 8.894 df 1 Sig 0.003 The test is significant and as such we reject the hypothesis that the proportions of the variable smoking status during pregnancy are significantly equal p-value = 0.003 < 0.05. The proportion of smokers and non-smokers are not significantly equal. Test Statistic Race of Mother Chi-Square 39.27 df 2 Sig 0.000 The test is significant and as such we reject the hypothesis that the proportions of the variable race are significantly equal p-value = 0.000 < 0.05. The proportion of white, black, and other are not significantly equal. Smoking status during pregnancy N Mean Std. Deviation S.E Mean Birth weight No 115 3054.96 752.409 70.163 Yes 74 2773.24 660.075 76.732 An observation of the group statistics indicate that the mean birth weight for mothers who did not smoke during pregnancy is significantly higher than the average birth weight of mothers who smoked during pregnancy. The independent samples t-test will have to be interpreted to evaluate if this difference is statistically significant. Independent samples t-test Levene’s Test F Sig t df Sig Equal variances 1.508 0.221 2.634 187 0.009 Birth weight Not equal variances 2.709 170.001 0.007 The independent samples t-test is statistically significant (p-value = 0.007) which indicates that the birth weight of infants whose mothers who smoked during pregnancy is significantly less than the birth weight of mothers who did not smoke during pregnancy. The null hypothesis is rejected at 0.05 significance level and the alternative hypothesis that the birth weights of infants from mothers who smoked during pregnancy is different from the birth weight of mothers who did not smoke is accepted. Birth weight in grams Race of mother N Subset for alpha = 0.05 1 2 Black 26 2719.69 Other 67 2804.01 2804.01 White 96 3103.74 ANOVA Birth weight in grams Sum of Squares df Mean Square F Sig Between groups 5070607.632 2 2535303.816 4.972 0.008 Within groups 94846445.013 186 509927.124 Total 99917052.646 188 The ANOVA output is statistically significant in evaluating for differences in the categories of the variable race, F (2, 186) = 4.972, p > 0.05, p-value = 0.008. The null hypothesis that the proportions of the categories of the variable race are the same is rejected. The ANOVA results suggest that the proportions of the categories of the variable race are different. And evaluation of the significance in the difference is evaluated to ascertain which categories contribute to the ANOVA findings. (I)Race of Mother (J) Race of Mother Difference (I-J) Std. Error Sig Black 384.047 145.621 0.034 White White 299.725 115.247 0.031 White -384.047 145.621 0.034 Black Other -84.323 153.148 0928 White -299.725 115.247 0.031 Other Black 84.323 153.148 0.928 Observations of the categories of race indicate that the proportions of race are significantly different. The test for a difference in the categories black and white is significant p-value = 0.034 which is less than 0.05 significance value. The null hypothesis that the quantities of the proportions are similar for the categories black and white is rejected. The test for a difference in the categories other and white is significant p-value = 0.031 which is less than 0.05 significance value. The null hypothesis that the quantities of the proportions are similar for the categories white and other is rejected. The test for a difference in the categories black and other is not statistically significant p-value = 0.928 which is greater than 0.05 significance value. The null hypothesis that the quantities of the proportions are similar is accepted and it is concluded that the proportions of the categories black and other in the variable race are similar. The post hoc results indicate a difference in the results indicate that the birth weight of infants born by white mothers was significantly higher than the birth weight of infants born from the other categories. Similarly, the birth weight of infants born from the category ‘other’ was significantly higher than the birth weight of infants born from the category black. The birth weights were identified to be 3103.74, 2804.01, and 2719.69 for the white, other, and black mothers respectively. Conclusion and limitations The study was able to confirm that a relationship exists between maternal tobacco smoking and reduced birth weight of infants. Additionally, the birth weights of infants were shown to significantly differ across the categories of race. The result was unexpected because previous research has indicated that the weight of blacks is significantly higher than the weight of the other categories of race. However, in this analysis the birth weight of infants born from black mothers was significantly less than the average infant weight. There is a possible contribution to this and if this research was to be conducted again the researchers should evaluate occupation, socioeconomic status and other environmental factors. The findings of the study also indicate that the categories of the variables smoking status during pregnancy and race were significantly skewed. The number of mothers who smoked during pregnancy was significantly less than the number of women who did not smoke. The comparison of the two will consequently favor the mothers who did not smoke. Consequently the fact that the categories are not equal may lead to incorrect findings and conclusions. Similarly, the category white in the variable race had significantly higher proportion that the other categories. Future research should, evaluate the categories of these variables to ensure an unbiased comparison. References: Chiolero, A., Bovet, P., & Paccaud, F. (2005) ‘Association between maternal smoking and low birth weight in Switzerland: the EDEN study’, SWISS MED WEEKLY 2005; 135: 525-530 Wahabi, H., Alzeidan, R., Fayed, A., Mandil, A., Al-Shaikh, & Esmaeil, S. (2013) ‘Effects of secondhand smoke on the birth weight of term infants and the demographic profile of Saudi exposed women’, BMC Public Health 2013, 13:341 Ward, C., Lewis, S., & Coleman, T. (2007) ‘Prevalence of maternal smoking and environment tobacco smoke exposure during pregnancy and impact on birth weight: retrospective study using Millennium Cohort’, BMC Public Health 2007, 7:81 doi:10.1186/1471-2458-7-81 Read More