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Eczema is a common chronic disease in children, characterized by recurrent episodes of skin lesion and pruritus (1). Eczema is the first manifestation of “atopic march” and can lead to a higher risk of developing other allergic diseases later in life (2). However, the epidemiologic characteristics of eczema in very early life are still unclear. This study estimated the incidence of very-early onset of eczema, defined as diagnosed before six weeks of age, among infants born in Guangzhou, China, between 2018 and 2019, and it explored its related prenatal risk factors. The incidence of very-early-onset eczema was 12.4% in this population, and primiparity was associated with a higher risk of eczema {relative risk (RR) [95% confidence interval (CI)]: 1.23 (1.06–1.42)}. These findings indicate prenatal factors could have an important role in the development of infant eczema. The high incidence of infant eczema should receive more attention, and more research is needed to investigate the etiology of infant eczema and explore potential primary prevention strategies.
The present study was based on data collected from the Born in Guangzhou Cohort Study (BIGCS), which is a prospective birth cohort study conducted by the Guangzhou Women and Children’s Medical Center (GWCMC), China. Women were recruited during their first routine antenatal appointment (<20 weeks of gestation) at two different sites of GWCMC. Mother-infant dyads were included for this analysis if the infant was born between January 2018 and December 2019 and completed a follow-up at six weeks of age. Exclusion criteria excluded mothers with multiple pregnancies, withdrawn from the study after delivery, or whose infants died during the first six weeks postpartum. The Institute Ethics Committee of GWCMC has approved the study, and all participants provided written informed consent at enrollment.
The outcome of interest was very-early-onset eczema (i.e., eczema onset before 6 weeks of age). Information on infant eczema was collected via a self-administrative questionnaire modified from the validated version of International Study of Asthma and Allergies in Childhood. The parents were asked to choose yes or no to the question “has your child ever had atopic eczema diagnosed by a physician after birth?” during a follow-up at six-weeks postpartum. Other maternal information, including demographic characteristics, environmental exposure, and health conditions during pregnancy, was collected at enrollment via a validated questionnaire. Pre-pregnancy body mass index (BMI) (kg/m2) was categorized into four groups: underweight (BMI <18.5 kg/m2), normal (BMI 18.5–23.9 kg/m2), overweight (BMI 24.0–27.9 kg/m2), and obesity (BMI ≥28.0 kg/m2) based on Chinese standards (3). Differences in participants’ characteristics by infant eczema status (yes/no) were examined using the chi-squared test for categorical data and Student’s t-test for continuous variables. The incidence of eczema was calculated by dividing the number of infants diagnosed with eczema by the total number of infants included in the analysis. Poisson regression models were performed to investigate the association between potential risk factors and very-early-onset eczema, and RR and 95% CI were calculated. Statistical analyses were performed using SAS (version 9.4, SAS Institute Inc., Cary, NC, USA).
A total of 10,085 singleton-born infants [follow-up rate of 90.6% (10,085/11,130)] had information on eczema diagnosis at six weeks of age and were included in the current analysis. Among these infants, 12.4% (n=1,247) had very-early-onset eczema. Table 1 summarized the maternal and infant characteristics by very-early-onset eczema status (yes/no). The incidence of very-early-onset eczema among infants of primiparous mothers was higher than that among infants of multiparous mothers (13.4% vs. 10.8%, P<0.01). Statistically significant differences were not found between infants with or without very-early-onset eczema in other maternal and infant characteristics, including maternal age, maternal monthly income, maternal education level, pre-pregnancy BMI, tobacco exposure during early pregnancy, maternal history of allergy, pets during pregnancy, proportion of cesarean section, gestational diabetes mellitus, hypertensive disorders in pregnancy, gestational age, and infant sex. Results for associations of each potential prenatal risk factor with very-early-onset eczema were also shown in Figure 1. Primiparity was associated with increased risk of very-early-onset eczema [RR (95% CI): 1.23 (1.06–1.42)]. No statistically significant association was found for other prenatal factors.
Characteristics With very-early-onset eczema (n=1,247) Without very-early-onset eczema (n=8,838) P-value Maternal age, years, mean±SD 30.5±3.8 30.6±4.0 0.30 Maternal monthly income, CNY, n (%) 0.22 ≤1,500 91(8.1) 685(8.4) 1,501–4,500 130(11.6) 1,115(13.6) 4,501–9,000 454(40.5) 3,305(40.4) ≥9,001 447(39.8) 3,078(37.6) Maternal education level, n (%) 0.08 Middle school or below 78(6.3) 721(8.2) College 283(22.7) 2,017(22.8) Undergraduate 673(54.0) 4,724(53.5) Postgraduate or above 213(17.1) 1,376(15.6) Pre-pregnancy BMI, kg/m2, n (%) 0.65 <18.5 241(20.9) 1,645(19.9) 18.5–23.9 783(68.0) 5,631(68.2) 24.0–27.9 110(9.6) 828(10.0) ≥28.0 17(1.5) 155(1.9) Tobacco exposure during early pregnancy, n (%) 323(27.1) 2,309(26.8) 0.85 Drinking during early pregnancy, n (%) 63(5.3) 436(5.1) 0.75 Maternal history of allergy, n (%) Eczema 81(6.8) 517(6.0) 0.31 Rhinitis 195(16.3) 1,329(15.4) 0.45 Asthma 9(0.8) 40(0.5) 0.19 Pets during pregnancy, n (%) 171(14.2) 1,144(13.3) 0.35 Cesarean section, n (%) 336(27.0) 2,485(28.2) 0.37 Primipara, n (%)* 814(65.3) 5,243(59.3) <0.01 Gestational diabetes mellitus, n (%) 211(17.0) 1,477(16.8) 0.88 Hypertensive disorders in pregnancy, n (%) 61(4.9) 401(4.6) 0.59 Gestational age, weeks, mean±SD 39.3±1.2 39.2±1.4 0.11 Male child, n (%) 672(53.9) 4,603(52.1) 0.25 Abbreviations: BMI=body mass index; SD=standard deviation.
* Statistically significant.Table 1. Maternal and infant characteristics according to very-early-onset eczema in Guangzhou, Guangdong, China, 2018–2019.
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