Sex ratio at birth: scenario from normal- and high-level natural radiation areas of Kerala coast in south-west India.
Newborns were monitored for congenital malformations in four government hospitals located in high-level (ambient dose >1.5 mGy/year) and normal-level (≤ 1.5 mGy/year) natural radiation areas of Kerala, India, from August 1995 to December 2012. Sex ratio at birth (SRB) among live singleton newborns and among previous children, if any, of their mothers without history of any abortion, stillbirth or twins is reported here. In the absence of environmental stress or selective abortion of females, global average of SRB is about 1050 males to 1000 females. A total of 151,478 singleton, 1031 twins, 12 triplets and 1 quadruplet deliveries were monitored during the study period. Sex ratio among live singleton newborns was 1046 males (95 % CI 1036-1057) for 1000 females (77,153 males:73,730 females) and was comparable to the global average. It was similar in high-level and normal-level radiation areas of Kerala with SRB of 1050 and 1041, respectively. It was consistently more than 1000 and had no association with background radiation levels, maternal and paternal age at birth, parental age difference, gravida status, ethnicity, consanguinity or year of birth. Analysis of SRB of the children of 139,556 women whose reproductive histories were available suggested that couples having male child were likely to opt for more children and this, together with enhanced rate of males at all birth order, was skewing the overall SRB in favour of male children. Though preference for male child was apparent, extreme steps of sex-selective abortion or infanticide were not prevalent.
Low Level Radiation Research Laboratory, Low Level Radiation Research Section, Radiation Biology & Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Beach Road, Kollam, 691 001, India. pkmkoya@yahoo.com.
P K M
http://orcid.org/0000-0002-8596-1235
PK
Koya
Low Level Radiation Research Laboratory, Low Level Radiation Research Section, Radiation Biology & Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Beach Road, Kollam, 691 001, India.
G
G
Jaikrishan
Low Level Radiation Research Laboratory, Low Level Radiation Research Section, Radiation Biology & Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Beach Road, Kollam, 691 001, India.
K R
KR
Sudheer
, Kollam, 691 001, India.
V J
VJ
Andrews
Department of Paediatrics, Victoria Hospital, Kollam, 691 001, India.
M
M
Madhusoodhanan
Directorate of Health Services, Thiruvananthapuram, 695 035, India.
C K
CK
Jagadeesan
Low Level Radiation Research Section, Radiation Biology & Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Mumbai, 400 085, India.
Birajalaxmi
B
Das
D000016:Abnormalities, Radiation-Induced / Q000453:epidemiology*; D001417:Background Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D015995:Prevalence; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis / Q000706:statistics & numerical data*; D011834:Radiation Monitoring / Q000706:statistics & numerical data; D018570:Risk Assessment; D012744:Sex Ratio
Gender preference; High-level natural radiation; Reproductive health; Sex ratio at birth