Table 1 Description of independent variables

Biodemographic and socioeconomic variables

Age (in years)

Age of women was divided into four categories: ‘15–19 years’ (coded as ‘1’), ‘20–29 years’ (coded as’2’), ‘30–29 years’ (coded as ‘3’), ‘40–49 years’ (coded as ‘4’).

Marital status

Marital status has divided into three categories: ‘currently married’ (coded as ‘1’), ‘not married’ (coded as ‘2’), ‘formerly married’ (coded as ‘3’).

Parity

Parity was categorized into four: ‘no children’ (coded as ‘0’), ‘1–2 children’ (coded as ‘1’), ‘3–4 children’ (coded as ‘2’), ‘5 and above’ (coded as ‘3’).

Breastfeeding status

Breastfeeding status was categorized into two: ‘not breastfeeding’ (coded as ‘0’), ‘breastfeeding’ (coded as ‘1’).

Pregnancy status

Pregnancy status had two categories: ‘not pregnant’ (coded as ‘0’), ‘pregnant’ (coded as ‘1’).

Level of education

Education level of women was classified into four categories: ‘no education’ (coded as ‘0’), ‘primary’ (coded as ‘1’), ‘secondary’ (coded as ‘2’), ‘higher’ (coded as ‘3’).

Social groups

Social groups were divided into four categories: Scheduled Caste (SC) (coded as ‘1’), Scheduled Tribe (ST) (coded as ‘2’), Other Backward Classes (OBC) (coded as ‘3’), ‘Others’ (coded as ‘4’).

Religion

Religion was divided into four categories– ‘Hindu’ (coded as ‘1’), ‘Muslim’ (coded as ‘2’), ‘Christian’ (coded as ‘3’) ‘Others’ (coded as ‘4’).

Household wealth

The wealth index is a composite index of household amenities and assets; it indicates the socioeconomic condition; every household is given a score based on the number of consumer goods they own. A total of 33 assets and housing characteristics were taken into consideration to prepare a factor score using Principal Component Analysis. Thereafter this factor score was divided into five equal categories, − ‘poorest’ (coded as ‘1’); ‘poorer’ (coded as ‘2’); ‘middle’ (coded as ‘3’); ‘richer’ (coded as ‘4’); ‘richest’ (coded as ‘5’) each with 20% of the population.

Type of place of residence

Place of residence had two categories: ‘urban’ (coded as ‘0’), ‘rural’ (coded as ‘1’).

Behavioral variables

Mass media exposure

Three questions were asked to women in NFHS-4 and NFHS-5. They are i) how often they read newspaper/magazines, ii) how often they watch television, and iii) how often they listen to radio. The responses are ‘almost every day’, ‘at least once a week’, ‘less than once a week’ and ‘not at all’. Based on these responses a composite index was computed and divided into four categories: ‘no’ (coded as ‘0’) if the respondent is not exposed to any mass media, ‘low’ (coded as ‘1’) if a respondent is exposed to any one type of mass media, ‘medium’ (coded as ‘2’) if the respondent is exposed to any two types of mass media, ‘high’ (coded as ‘3’) if the respondent is exposed to all three types of mass media.

Frequency of eating eggs

This variable was classified into three categories: ‘never’ (coded as ‘0’), ‘frequently’ (coded as ‘1’), ‘occasionally' (coded as ‘2’).

Frequency of eating fish

Frequency of eating fish was classified into three categories: ‘never’ (coded as ‘0’), ‘frequently’ (coded as ‘1’), ‘occasionally' (coded as ‘2’).

Frequency of eating chicken

This variable was classified into three categories: ‘never’ (coded as ‘0’), ‘frequently’ (coded as ‘1’), ‘occasionally' (coded as ‘2’).

Current contraceptive use

NFHS classified the contraceptive into 20 categories, all these categories. All these responses was recoded into two categories for this study: ‘no or traditional’ contraceptive use (coded as ‘0’), if a woman did not use anything or used periodic abstinence, withdrawal, other traditional method, or prolonged abstinence to delay or avoid getting pregnant; and ‘modern’ contraceptive use (coded as ‘1’) if a woman used pill, intrauterine device, injections, diaphragm, male condom, female sterilization, male sterilization, implants/norplant, lactational amenorrhea method, female condom, foam or jelly, emergency contraception, other modern method, standard days method, specific method 1, or specific method 2.

Alcohol consumption

Alcohol consumption was divided into two categories: ‘no’ (coded as ‘0’), ‘yes’ (coded as ‘1’)

Health related variables

Body Mass Index

It is defined as the ratio between the weight of a women in kilogram divided by the squared height in meter. Body mass index was divided into four categories according to WHO cutoff; underweight (< 18.5 kg/m²) coded as ‘1’, normal (18.5 kg/m²–24.99 kg/m²) coded as ‘2’, overweight (25 kg/m²–32 kg/m²) coded as ‘3’ and obese (> 32 kg/m²) coded as ‘4’ [58].

Currently having diabetes

Self-reported diabetes had three categories: ‘no’ (coded as ‘0’) ‘yes’ (coded as ‘1’) ‘don’t know’ (coded as ‘8’).

Currently amenorrheic

Amenorrhea is the absence of menstruation, typically defined by the absence of one or more menstrual cycles. Amenorrhea had two categories: ‘no’ (coded as ‘0’), ‘yes’ (coded as ‘1’)

Year

NFHS-4, conducted during 2015-16 was coded as ‘0’ and NFHS-5, conducted during 2019-21 was coded as ‘1’.