Mortality risk of small infants varies with their mother's birthweight and race

We analysed a transgenerational linked birth file to investigate the relationship between maternal birthweight and infant birthweight-specific mortality risk for white and African American infants. Birth records of 267,303 infants born between 1989 and 1991 were linked to records of their mothers, born between 1956 and 1976, and to their own death certificates for those dying in the first year. The means, standard deviations and z-scores were calculated for each race- and generation-specific birthweight distribution. Investigators then analysed the mortality of very small infants (birthweight at least two standard deviations below their mean) for three maternal birthweight categories. Over half of the infant deaths involved births with weights more than two standard deviations below the relevant population mean birthweight (comprising 4.2% of white and 6.9% of African American births respectively). African American infants experienced higher mortality rates at all levels of standardised birthweight, from z-scores of -3 to +3. The relative risk of mortality associated with very small infant size was less for infants delivered to smaller birthweight mothers when compared with those whose mothers were average sized or large at birth. This differential effect was confined to neonatal deaths and was more prominent in the white subpopulation.     

Birthweight and early neonatal health: Bangladesh perspective

It has been suggested that a birthweight limit of 2.5 kg should not be regarded as valid for all populations as the cut-off point of low-weight births because of demographic, genetic and environmental differences. Countries often choose alternative cut-off values for low birthweight for clinical purposes. Bangladesh also needs to choose a convenient cut-off value for low birthweight. A total of 770 live singleton full-term normal newborns were included in this study by stratified sampling; birthweight was measured using the Detecto-type baby weight machine. Newborns were followed up to the end of their first week of life. For data collection a pretested structured questionnaire and an Apgar Score estimating checklist were used. Chi-square test was applied to assess the association of different birthweight strata and neonatal health outcomes. Multiple logistic regression analyses were carried out to identify the independent effects of different levels of birthweight on early neonatal health.
The neonates having birthweight ≤2 kg had a significantly higher risk of early neonatal mortality and morbidity than the higher level birthweight group. Birth asphyxia was the commonest cause of early neonatal mortality and morbidity. Borderline birthweight (>2 to <2.5 kg) neonates experienced the same mortality and morbidity rates as the normal birthweight neonates during their early neonatal life. Birthweight ≤2 kg may be one of the criteria for admission to a neonatal intensive care unit whereas more than 2 kg may not require admission unless otherwise necessary.     

"Development" is not essential to reduce infant mortality rate in India: experience from the Ballabgarh project

BACKGROUND: India aims to reduce the infant mortality rate (IMR) to below 60 per 1000 live births by 2000. IMR is higher in northern India as compared with south Indian states like Kerala. Any further reduction in IMR needs identification of new strategies. The Ballabgarh project with an IMR of 36 in 1997 can help identify such strategies. OBJECTIVE: To see the trend in reduction of neonatal mortality rate (NNMR) and IMR at the Ballabgarh project, compare it with Kerala and rural India's trend and look at the causes of neonatal and infant mortality. DESIGN: The Comprehensive Rural Health Services Project, Ballabgarh, run by the All India Institute of Medical Sciences, covered an estimated population of 70,079 in 1997. The health care delivery system is on the national pattern. All the deaths are identified during the house visits by the male workers. The cause of death is ascertained by the health assistant based on the symptomatology at the time of death. RESULTS: The trends in reduction of IMR for Ballabgarh, Kerala and rural India are roughly parallel with the IMR of Ballabgarh lying somewhere in between the two. However, the NNMR of Ballabgarh (10.6 in 1996) was comparable to Kerala's NNMR (10.9 in 1992). The proportion of infant deaths occurring during the neonatal period had fallen from 50% in the early seventies to 30% during 1996-97. In 1992-1994, 33.8% of all neonatal deaths were attributable to low birth weight and 37.3% to infective causes. Acute respiratory infection and diarrhoea continue to be the chief cause of postneonatal mortality. CONCLUSION: It is possible to bring down neonatal mortality before postneonatal mortality. The Kerala model, which focuses on social development, may not apply to northern India for sociocultural reasons.     

The effect of income inequality and macro-level social policy on infant mortality and low birthweight in developed countries--a preliminary systematic review

Objective To carry out a preliminary systematic review of literature to address the question – among rich nations (or states within nations) what is the evidence that income inequality and differences in macro‐level social policy affect rates of infant mortality and low birthweight (LBW)? Study design A systematic literature review. Search strategy Medline database (1968–August 2003) was searched for empirical studies of the relationship between macro‐level economic and social policies in rich nations and rates of infant mortality (IMR) and LBW. Cross‐national comparison of infant mortality and LBW that did not compare the effects of macro‐level economic and social policies was excluded from the review as were studies including less developed countries. Keywords representing IMR and LBW were entered into Medline along with exposures related to international comparison and macro‐level policy. Abstracts obtained from the initial search were reviewed for relevant studies. Full papers of potentially relevant studies were obtained and reviewed for inclusion. Secondary search of papers cited in included papers was undertaken. For this review, papers were not excluded on the basis of quality although methodological limitations were commented on and taken into account in interpreting the results. Summary statistics were not estimated. Results Twelve studies, fulfilling the inclusion criteria, were identified. Ten studies examined the association of IMR with income inequality, eight of which reported a statistically significant positive association with higher levels of inequality after adjustment for a range of variables. Six studies reported significant positive associations of IMR with other indicators of less re‐distributive social and economic policy. Associations with LBW were reported in four studies; three showed significant positive associations with higher levels of income inequality and one showed no association with low levels of parental leave entitlement. Methodological differences, particularly the wide range of variables used to adjust for confounding, make interpretation of the findings difficult. Conclusions The results of this review represent a preliminary attempt to summarize the literature linking macro‐level economic and social policies in rich nations with IMR and LBW. The findings, taking account of the methodological limitations of the review and of the included studies, suggest a statistically significant association between IMR and higher income inequality and other indicators of less re‐distributive social policy. Only three studies examined the association of income inequality with LBW and, although they suggest a significant association, further studies will be needed to confirm this finding.     

Effect of maternal asthma on birthweight and neonatal outcome in a British inner-city population

During pregnancy, asthma-related alterations in placental function and the maternal immune system, and reduced growth affecting female but not male fetuses have been reported in a study of selected Australian women. The objective of this study was to evaluate the effect of asthma management, declared during pregnancy, on birthweight and neonatal outcome at an inner-city hospital in England. Between June 2001 and December 2003, women at antenatal clinics were questioned about asthma (n = 10 983). Women with asthma and singleton uncomplicated pregnancies ending at term were selected (n = 718), with non-asthmatic controls (n = 718). Among asthmatic women using inhaled steroids and bronchodilators (n = 170), 43% of the newborn boys had birthweights <10th centile, compared with 27% of controls (P = 0.011; OR 2.51 [95% CI: 1.52, 4.14]). For girls, the proportions were 28% and 27%. In women using bronchodilators only (n = 178) or those declaring no treatment (n = 370), birthweights were not significantly reduced. Taking account of smoking, ethnicity, gestational age and parity, there was a mean birthweight reduction with inhaled steroids and bronchodilators of 118 g [95% CI 36.0, 199.0 g] compared with the control group. There was no interaction between the effect of asthma treatment and infant gender. Infants of asthmatic women in the three subgroups who required intensive care were more likely to exhibit transient tachypnoea of the newborn than infants of control women (P < 0.005). In our population-based sample, the risk of low birthweight among asthmatic women did not depend on infant gender, while neonatal respiratory morbidity remains a significant health issue in boys and girls.     

Stillbirth and infant mortality in singletons by cause of death,birthweight, gestational age and birthweight‐for‐gestation,Newcastle upon Tyne 1961–2000

Glinianaia SV, Rankin J, Pearce MS, Parker L, Pless‐Mulloli T. Stillbirth and infant mortality in singletons by cause of death, birthweight, gestational age and birthweight‐for‐gestation, Newcastle upon Tyne 1961–2000. Paediatric and Perinatal Epidemiology 2010. The dramatic reduction observed in stillbirth and infant mortality over the last few decades has not been assessed by both birthweight and gestation. We have explored temporal changes in stillbirth and infant mortality in Newcastle upon Tyne, UK, by cause of death, birthweight, gestational age, birthweight standardised for gestation and infant sex during 1961–2000. We included 131 044 singleton births to mothers resident in Newcastle, including 1342 stillbirths and 1620 infant deaths. Cause‐, birthweight‐, gestational age‐ and birthweight‐for‐gestation‐specific stillbirth (per 1000 total births) and infant mortality (per 1000 livebirths) rates were compared between 1961–80 and 1981–2000 and between individual consecutive decades. Between 1961 and 2000, total stillbirth and infant mortality rates declined dramatically from 23.4 to 4.7 per 1000 total births and from 25.7 to 5.9 per 1000 livebirths, respectively. Rates fell continuously during the first two study decades; however, from 1981–90 to 1991–2000 the decline was not statistically significant. Between 1961–80 and 1981–2000, both stillbirth and infant mortality significantly declined in all birthweight and gestational age categories and for most leading causes of death. Although the population mean birthweight during 1981–2000 [3304 g (SD ± 569)] was significantly higher than during 1961–80 [3255 g (SD ± 572)] (P < 0.0001), the lowest stillbirth and infant mortality rates in 1981–2000 were consistently at about 1 SD above the mean birthweight, with mortality rates increasing for babies with lower or higher weight‐for‐gestation. Declines in stillbirth and infant mortality in Newcastle were associated with reductions in birthweight‐ and gestational age‐specific mortality rates and occurred in most cause‐specific groups of death.     

Early neonatal mortality, low birth weight and related factors in Japan

Objectives The author conducted an ecological study to examine prefectural differences in ENMR and the related factors in Japan, using two new indicators; birth weight (BW) adjusted ENMR and expected ENMR by BW distribution. Method Correlate analysis of data from national vital statistics and some indicators of medical care services among 47 prefectures edited by the Ministry of Health and Welfare, Japan were conducted. BW-adjusted ENMR and expected ENMR by BW, as well as other indicators, were prepared for statistical analysis. Result Crude and BW-adjusted ENMRs were significantly correlated with ENMRs for low birth weight (LBW) and very low birth weight (VLBW) early neonates (p<0.01). The number of Obstetrics and Gynecology (OB/GYN) physicians was negatively correlated with BW adjusted ENMR. Conclusion Crude and BW-adjusted ENMRs were affected mainly by LBW and VLBW early neonate specific ENMR, but not by the rate of LBW. The variation of ENMR among prefectures in Japan is attributable to the number of OB/GYN physicians. The present findings suggest that emphasis should be laid upon enhancement of regional perinatal care systems.     

Obstetrical volume and early neonatal mortality in preterm infants

Objective Regionalised perinatal care with antenatal transfer of high risk pregnancies to Level III centres is beneficial. However, levels of care are usually not linked to caseload requirements, which remain a point for discussion. We aimed to investigate the impact of annual delivery volume on early neonatal mortality among very preterm births. Methods All neonates with gestational age 24–30 weeks, born 1991–1999 in Lower Saxony were included into this population-based cohort study (n = 5,083). Large units were defined as caring for more than 1,000 deliveries/year, large NICUs as those with at least 36 annual very low birthweight (<1,500 g, VLBW) admissions. Main outcome criterion was mortality until day 7. Adjusted Odds Ratios (adj. OR) and 95% confidence intervals (CI) were calculated based on generalised estimating equation models, accounting for correlation of individuals within units. Results Within the first week of life, 20.6% of all neonates deceased; 10.2% were stillbirths, 3.7% died in the delivery unit, and 6.7% in the NICU. The crude OR for early neonatal mortality after having been delivered in a small delivery unit (excluding stillbirths) was 1.36 (95%CI 1.04–1.78; adj. OR 1.16 (0.82–1.63)). It increased to 1.96 (1.54–2.48; adj. OR 1.21 (0.86–1.70)) after the inclusion of stillbirths. Conclusion This study has shown a slight, but non-significant association between obstetrical volume and early neonatal mortality. In future studies the impact of caseload on outcome may become more evident when referring to high-risk patients instead of to the overall number of deliveries.     

A study of infant mortality in Greenwich: A comparison of the infant mortality rates of wards within Greenwich after allowance for deprivation

Using 1981 census data for Greenwich plus OPCS statistics on infant deaths in Greenwich (1981–1989) this paper describes the construction of ‘corrected’ infant mortality rates for wards within Greenwich after allowing for the deprivation experienced within each ward. It is hoped that these simple methods could be used to identify those areas which merit further investigation without resorting to more complicated statistical methods. It would then be possible to investigate whether interventions are helping or are other factors involved? Finally regression analyses are used in order to understand the many factors involved in the measured deprivation and the inter-relationships between them.     

Associated factors and consequences of late preterm births: results from the 2004 Pelotas birth cohort

Although neonatal and infant mortality rates have fallen in recent decades in Brazil, the prevalence of preterm deliveries has increased in certain regions, especially in the number of late preterm births. This study was planned to investigate: (1) maternal antenatal characteristics associated with late preterm births and (2) the consequences of late preterm birth on infant health in the neonatal period and until age 3 months. A population-based birth cohort was enrolled in Pelotas, Southern Brazil, in 2004. Mothers were interviewed and the gestational age of newborns was estimated through last menstrual period, ultrasound and Dubowitz's method. Preterm births between 34 and 36 completed weeks of gestational age were classified as late preterm births. Only singleton live births from mothers living in the urban area of Pelotas were investigated. Three months after birth, mothers were interviewed at home regarding breast feeding, morbidity and hospital admissions. All deaths occurring in the first year of life were recorded. A total of 447 newborns (10.8%) were late preterms. Associations were observed with maternal age <20 years (prevalence ratio [PR] 1.3 [95% CI 1.1, 1.6]), absence of antenatal care (PR 2.4 [1.4, 4.2]) or less than seven prenatal care visits, arterial hypertension (PR 1.3 [1.0, 1.5]), and preterm labour (PR 1.6 [1.3, 1.9]). Compared with term births, late preterm births showed increased risk of depression at birth (Relative risk [RR] 1.7 [1.3, 2.2]), perinatal morbidity (RR 2.8 [2.3, 3.5]), and absence of breast feeding in the first hours after birth (PR 0.9 [0.8, 0.9]). RRs for neonatal and infant mortality were, respectively, 5.1 [1.7, 14.9] and 2.1 [1.0, 4.6] times higher than that observed among term newborns. In conclusion, in our setting, the prevention of all preterm births must be a priority, regardless of whether early or late.     

Prologue: Closing the Gap,Opening the Process: Why Study Social Contributors to Preterm Delivery Among Black Women

In the United States, the excess rates of infant mortality, VLBW, and preterm delivery among African American families relative to white families are known as the gap. A group of researchers in the Division of Reproductive Health at the Centers for Disease Control and Prevention proposed that the study of causes of the gap in preterm delivery and the potential interventions to eliminate this disparity required a multidisciplinary approach to elucidate the biologic pathways, stressors, and social environment associated with preterm birth. They encouraged studies that examined the social and political impact of being an African American woman in the United States, racism, and the combined effects of gender, racism, and relative social position, as potential unmeasured etiologic factors that contribute to the gap. The studies conducted represent the expertise of anthropologists, sociologists, medical researchers, and epidemiologists who study both individual and social causes and then also provide a theoretical interpretation by those who lived the experience, (e.g., the study participants) rather than just the researchers' interpretation of the causes of and prevention strategies for the gap.     

新生儿危重病例评分和第三代小儿死亡危险评分预测危重新生儿死亡风险比较

目的 比较第三代小儿死亡危险评分(pediatric risk of mortality III score, PRISM III)和新生儿危重病例评分(neonatal critical illness score, NCIS)在预测危重新生儿死亡风险方面的优越性, 探讨更适合我国NICU应用的评分系统。方法 对2013年1-6月入住新疆石河子大学第一附属医院新生儿重症监护室(neonatal intensive care unit, NICU)的135例患儿同时采用NCIS和PRISM III两种评分系统进行评分, 根据评分将入组病例分为极危重、危重、非危重3组, 分别对各组病死率进行比较, 并描绘受试者工作特征曲线(receiver operating characteristic curve, ROC), 比较ROC曲线下面积(area under the ROC curve, AUC), 以观察两种评分系统在预测危重新生儿死亡风险的优越性。结果 NCIS评分与PRISM III评分非危重组、危重组与极危重组组间病死率比较, 差异均有统计学意义(P＜0.05);两种评分对应组组间比较, 差异均无统计学意义(P＞0.05);AUC:NCIS评分0.900, PRISM III评分0.909。结论 NCIS评分与PRISM III评分均能准确预测新生儿死亡风险, PRISM III评分在我国完全适用。     

Socioeconomic inequalities in perinatal and infant mortality from 1854 to 1990 in Amsterdam, the Netherlands

Trends in socioeconomic differences in infant and perinatalmortality in Amsterdam were studied for the period 1854–1990,using published and unpublished material, at the aggregate andat the individual level. Absolute and relative socioeconomicmortality differences (SEMD) per data-set were calculated usinginequality indices developed by Pamuk. The results show a decreaseof the absolute differences in both infant and perinatal mortality.For infant mortality, this is mainly due to the overall declineof the infant mortality rate. Relative differences in infantmortality did not decrease during the study period. This isthe result of separate developments in 3 time periods. Fromapproximately 1850 to approximately 1910 an increase in relativedifferences can be seen, a trend which is reversed from approximately1910 to the end of World War II. After World War II relativedifferences seem to stabilize at the same level. For perinatalmortality, for which only data from the post-World War II periodare available, the decrease in the absolute differences is dueboth to the overall decline of the perinatal mortality rateand to a decline of relative differences between socioeconomicgroups. It is conduded that although SEMD in infant and perinatalmortality have declined in an absolute sense, they still existand that the relative position of deprived groups concerninginfant mortality was not ameliorated during the study period.     

Right bundle branch block: Prevalence,incidence, and cardiovascular morbidity and mortality in the general population

Background: Right bundle branch block (RBBB) is among the most common electrocardiographic abnormalities.

Objectives: To establish the prevalence and incidence of RBBB in the general population without cardiovascular events (CVE) and whether RBBB increases cardiovascular morbidity and mortality compared with patients with a normal electrocardiogram (ECG).

Methods: A historical study of two cohorts including 2981 patients from 29 primary health centres without baseline CVE. Cox (for CVE) and logistic (for cardiovascular factors) regression was used to assess their association with RBBB.

Results: Of the patients (58% women; mean age 65.9), 92.2% had a normal ECG, 4.6% incomplete RBBB (iRBBB) and 3.2% complete RBBB (cRBBB). Mean follow-up was five years. Factors associated with appearance of cRBBB were male sex (HR?=?3.8; 95%CI: 2.4–6.1) and age (HR?=?1.05 per year; 95%CI: 1.03–1.08). In a univariate analysis, cRBBB was associated with an increase in all-cause mortality but only bifascicular block (BFB) was significant after adjusting for confounders. cRBBB tended to increase CVE but the results were not statistically significant. Presence of iRBBB was not associated with adverse outcomes. Patients with iRBBB who progressed to cRBBB showed a higher incidence of heart failure and chronic kidney disease.

Conclusion: In this general population cohort with no CV disease, 8% had RBBB, with a higher prevalence among men and elderly patients. Although all-cause mortality and CVE tended to increase in the presence of cRBBB, only BFB showed a statistically significant association with cRBBB. Patients with iRBBB who progressed to cRBBB had a higher incidence of CVE. We detected no effect of iRBBB on morbidity and mortality.     

Maternal exposure to ambient PM2.5 and term low birthweight in the State of Georgia

A growing body of evidence suggests that ambient air pollution could be associated with low birthweight (LBW). In this study, we examined pregnancy exposure to ambient PM_2.5 and the risk of LBW in the State of Georgia. The study population consisted of 48,172 full-term live births between 1 January 2004 and 31 December 2004 in nine counties of Georgia, which was obtained from the national natality dataset. County-level air quality index data obtained from the U.S. Environmental Protection Agency was used to estimate exposure to ambient levels of PM_2.5. Multivariate logistic regression revealed that infants with maternal exposure to PM_2.5 falling within 75 to < 95th percentiles were at increased risk of LBW (OR: 1.36; 95 % CI: 1.03, 1.79), after adjusting for potential confounders. This study provided more evidence on the role of PM_2.5 in LBW. Reducing exposure for pregnant women would be necessary to improve the health of infants.     

The historical roots of high rates of infant death in Aboriginal communities in Canada in the early twentieth century: the case of Fisher River, Manitoba

Infant mortality is investigated for a period of thirty years at the beginning of the 20th century in the Aboriginal Nations community of Fisher River, Manitoba. Infant mortality rates were generated from parish records of infant burials from the Methodist mission at Fisher River and later archived at the United Church Archives in Winnipeg, Man. The average infant mortality rate (IMR) for the total period (1910-1939) was 249 per 1000 live births, an exceedingly high rate compared to modern IMRs and even higher than those in developing countries today. Acute respiratory infections were found to be the cause of death in the majority of cases. These infectious diseases and high rates of postneonatal infant mortality point to conditions of poverty associated with malnutrition as the major precipitating factor in infant death. Fisher River, like other early 20th century First Nations communities in Canada, experienced socio-economic deprivation because of the decline of the fur trade and the underdevelopment of a reserve economy competing for resources with the Canadian government and Euro-Canadian settlers. These conditions of economic and political marginalization are concluded to be the ultimate causes of high rates of infant mortality and are incorporated in a disease ecology model.     

Trends in stillbirths, early and late neonatal mortality in rural Bangladesh: the role of public health interventions

Trends were examined in a cohort study of stillbirths and early and late neonatal deaths in Matlab, a rural area of Bangladesh between 1975 and 2002, using routinely collected demographic surveillance data. Main outcome measures were stillbirths per 1000 births, early neonatal deaths per 1000 livebirths, and late neonatal deaths per 1000 children surviving after 1 week. We performed a logistic regression examining trends over time and between two areas in the three outcome measures, controlling for the effects of parental education, religion, time, geography, parity, maternal age and birth spacing. There was a marked decline in stillbirths, early and late neonatal mortality over time in both areas, though the pace of decline was somewhat faster in the ICDDR,B (International Centre for Diarrhoeal Disease Research, Bangladesh) service area. Stillbirths declined by 24% overall in the ICDDR,B service area (crude OR comparing 1996-2002 with 1975-81: 0.76 [95% CI 0.68, 0.84]), compared with 15% in the Government service area (crude OR comparing 1996-2002 with 1975-81: 0.85 [0.76, 0.94]). The overall reduction in early and late neonatal mortality comparing the same periods was 39% and 73%, respectively, in the ICDDR,B area, compared with 30% and 63%, respectively, in the Government service area. Adjusting for socio-economic or demographic factors did not substantially alter the time or area differentials. The dramatic decline in neonatal mortality was, in large part, due to a fall in deaths from neonatal tetanus. The pace of decline was faster in the area receiving intense maternal and child health and family planning interventions, but stillbirths, early and late neonatal deaths also declined in the area not receiving such intense attention, suggesting that factors outside the formal health sector play an important role.     

Perinatal mortality in relation to birthweight and gestational age: a registry-based comparison of Northern Norway and Murmansk County, Russia

The objective was to explore how perinatal mortality relates to birthweight, gestational age and optimal perinatal survival weight for two Arctic populations employing an existing and a newly established birth registry. A medical birth registry for all births in Murmansk County of North-West Russia became operational on 1st January 2006. Its primary function is to provide useful information for health care officials pertinent to improving perinatal care. The cohort studied consisted of 17,302 births in 2006-07 (Murmansk County) and 16,006 in 2004-06 (Northern Norway). Birthweight probability density functions were analysed, and logistic regression models were employed to calculate gestational-age-specific mortality ratios. The perinatal mortality rate was 10.7/1000 in Murmansk County and 5.7/1000 in Northern Norway. Murmansk County had a higher proportion of preterm deliveries (8.7%) compared to Northern Norway (6.6%). The odds ratio (OR) of risk of mortality (Northern Norway as the reference group) was higher for all gestational ages in Murmansk County, but the largest risk difference occurred among term deliveries (OR 2.45, 95% confidence interval 1.45, 4.14) which hardly changed on adjustment for maternal age, parity and gestation. Proportionately, more babies were born near (± 500 g) the optimal perinatal survival weight in Murmansk County (67.2%) than in Northern Norway (47.6%). The observed perinatal mortality was higher in Murmansk County at all birthweight strata and at gestational ages between weeks 25 and 42, but the adjusted risk difference was most significant for term deliveries.     

Differential susceptibility to effects of the home environment on motor developmental outcomes of preschool children: low birthweight status as a susceptibility factor

Low birthweight (LBW) children tend to have higher risks of developmental problems. According to differential susceptibility hypothesis, these putatively vulnerable children may also disproportionately benefit from positive environmental exposure. This study aimed to examine whether LBW status moderates home environmental influences on preschoolers’ motor development in a for-better-and-for-worse manner. Subjects included 18,717 children from the 2005 birth cohort in Taiwan. Birthweight was categorised into: lighter-LBW (LLBW, <2000?g), heavier-LBW (HLBW, 2000–2499?g) and non-LBW (NLBW, ≧2500?g) groups. Simple regression slopes indicated that LLBW and HLBW children demonstrated greater susceptibility than NLBW children to the effects of cognitive stimulation component of the home environment on both gross and fine motor skills. Estimating the regions of significance, however, revealed that LLBW and HLBW children appeared more vulnerable to less stimulating conditions, but did not outperform their NLBW counterparts when reared in enriched environments. Thus, our results did not support differential susceptibility.