The Sex Ratio At Birth And Its Associated Factors In Some Areas Of China

Objective:1. To investigate the situation about sex ratio at birth in some areas ofChina.2. To explore the associated factors about sex ratio at birth in some areas ofChina.3. Provide a scientific basis for the further research about family planning policyand making the strategies in maternal and children health work.Subjects and methods:1. Subjects: To explore the impact of the sex ratio at birth made by the familydesire gender and other factors, both Han’areas and minority’areas should be involved,Han is in the majority in the total sample population. Under the sampling principle,according to China’s administrative divisions, we used a multi-stage, stratified, randomcluster sampling method. At first,five provinces were randomly selected from NorthChina,Northeast China East China,Northwest China and Southwest China;then fivecities were randomly selected from five provinces above, the cities were Tongliao city,Harbin city,Changzhou city,Linxia city and Bijie city;then a district (county-level city)and a county were selected by using stratified random sampling during the selectedcities above,then we selected a street in the selected districts and counties randomly;Inthe end we used census to investgate the selected streets or towns.A total of16,954infants who were born from Jan1,2006to Dec31,2008and their parents were enrolledin our survey.2. Methods: The unified designed questionnaires were used to investigateretrospectively over by training investigators in the survey.The content of questionnaireincluded:(1) investigate the general situation of the infants and their parents;(2) infants and their mothers’ health status;(3) Mother’s induction of labor, abortion,including the factors of induction of labor;(4) the influencing factors of sex ratio atbirth under the parents’fertility desire. Statistical analysis:Epidata3.1software was used to establish a database, and all questionnaires wereinput after checking by two individuals. All p-values were based on a2-sided test and asignificance level of0.05, and statistical analysis was conducted using SPSS17.0statistical software.Results:1. A total of16,954infants were enrolled in our survey,according to the aim andquality,we got rid of the objects who had serious missing value.then the effectivenumber was16881.9196male infants,which accounting for54.48percent,and7685female infants, which accounting for45.52;The sex ratio at birth (SRB) was119.67,95%confidence interval was (116.05,123.30).2. The sex ratio at birth were differences in the distribution of populations andregions, were not differences in the distribution of time,including years andmonths.Han’s sex ratio at birth was116.8, while the minority’s sex ratio at birth is130.0,the sex ratio at birth of the ethnic minorities were significantly higher than Han’s (P=0.004),Analizing with different parity there was no different between different ethnicattributes when they were on the same patity,but all of the sex ratio at birth were deviatefrom the range of103-107.The sex ratio at birth were different (P <0.001) amongmother’s different education levels, the sex ratio at birth137.0(illiteracy) was muchhigher than the106.0(college and above), the trend test results: χ2=32.970, P <0.001,indicating that the sex ratio at birth gradually decreased with the mother’s educationincreasing;And sex ratio at birth was different among father’s education levels(P<0.001);The sex ratio at birth were different among mother’s differentoccupations(P<0.001), farmers were130.9, civil servants were101.5;The sex ratio atbirth were different among father’s occupations(P<0.001),Compared to mothers, civilservants’ sex ratio at birth was130.4, and the workers was the lowest (105.4);The sexratio at birth were significant different (P <0.001)among different parities, the trend testresults: χ2=68.294, P <0.001, indicating that the sex ratio at birth gradually increasedwith the mother’s parities increasing; The sex ratio at birth were different between thedifferent sex examination’s situation(P <0.001), sex ratio at birth(doing sex examination)was142.2,which was higher than114.7(without doing sex examination); The sex ratioat birth were different between mother whether did induction of labor, the sex ratio at birth up to160.7was significantly higher than113.9(mother without induction oflabor,P <0.001);The sex ratio at birth were different sex ratio at birth between motherwhether had a history of abortion,134.0(had a history of abortion)was higher than114.9(mother without history of abortion,P <0.001);The sex ratio at birth were differentamong parents’ different gender preference (P <0.001), Actually mothers who did notwant a baby,the sex ratio at birth up to158.0, while the mother preferred girls,the sexratio at birth was78.7;Fathers who did not want a baby,the sex ratio at birth up to152.0,while fathers preferred girls,the sex ratio at birth was69.8;The sex ratio at birth we hadinvestigated were different among the five cities(P<0.001),and Bijie was the highest(162.9),Tongliao was the lowest(107.7).3. Univariate logistic regression analysis showed that ethnic minorities, higherparity,mother had a history of abortion,mother had a history of induction oflabor,mother had a history of sex examination,mother did not want a baby,father did notwant a baby would increase the incidence of boys’ birth(OR:1.112~1.411; all P<0.05);parents’ education on higher level, mothers’ jobs liked workers, civil servants,business and other(compared to farmer) fathers’ occupation was workers, civilservants(compared to farmer), mothers preferred girls, fathers preferred girls wouldincrease the incidence of girls’b birth (OR:0.557~0.923;all P <0.05).4. Multiple logistic regression analysis showed that compared with the lowerparity,higher parity would increase the incidence of boys’ birth and its OR (95%CI) is1.348(1.239~1.466)(P <0.001);mother who had a history of induction of laborcompared mother who without a history of induction of labor would increase theincidence of boys’ birth and its OR (95%CI) is1.319(1.106~1.572)(P=0.002);Bigger expected number of children would increase the incidence of boys’ birthand its OR (95%CI) for0.758(0.709~0.811)(P <0.001);Mother preferred girlscompared to mother preferred other categories would increase the incidence of boys’birth and its OR (95%CI)0.740(0.661~0.829)(P <0.001);Father preferred girlscompared to Father preferred other categories would increase the incidence of girls’birth and its OR (95%CI) is0.679(0.597~0.773)(P <0.001).5. Compared to lower parity, higher parity would increase the incidence of sexexamination and its OR (95%CI) is3.033(2.841~3.238).6. Carrying out a sex examination would increase the incidence of abortion andinduction of labor, the respective OR (95%CI) are18.770(17.099to20.604)(P <0.001) and291.336(237.924~356.737)(P <0.001).7. The effect on the next baby’s gender caused by this gender we had investigatedin our survey: don’t want a baby as a reference, compared to boys’ family,girls’ familywant a boy’s OR (95%CI) is0.180(0.162~0.199)(P <0.001), girls’ family want agirl’s OR (95%CI) is6.262(5.479~7.157)(P <0.001),If the family think both boy andgirl could be all right,the OR (95%CI) is0.733(0.679~0.791)(P <0.001),this resultindicates that if the next baby would be born, boy’s family in our survey would like towant a girl baby.Conclusion:1. The sex ratio at birth (SRB) is out of the normal range (103~107), the sexratio at birth (SRB) was119.67,95%confidence interval was (116.05,123.30).2. The sex ratio at birth of the ethnic minorities were significantly higher thanHan’s, there was no different between different ethnic attributes when they were on thesame patity,but all of the sex ratio at birth were deviate from the range of103-107.3. The sex ratio at birth were different among parents’ different education levels,illiterate mother had the highest SRB,mother who got college and above had the lowestSRB,SRB gradually decreased with the mother’s education increasing;The sex ratio atbirth were different among parents’ different occupations.4. The sex ratio at birth we had investigated were different among the fivecities,and from highest to lowest is following: Bijie city,Harbin city,Linxiacity,Changzhou city,Tongliao city.5. The sex ratio at birth on different parity were differfent, compared with thelower parity,higher parity would increase the incidence of boys’ birth.6. Compared to lower parity, higher parity would increase the incidence of sexexamination;Compared to without a sex examination,Carrying out a sex examinationwould increase the incidence of abortion and induction of labor.7. Parents’ prefer gender would affect the sex ratio at birth;the gender of thefamily had would affect the next children’s gender preference.8. Parents’ ideal number of children would affect the sex ratio at birth,morechildren’s desire would decrease SRB.