Offspring Mean Research Articles

Association of maternal vitamin D status during pregnancy with bone-mineral content in offspring: a prospective cohort study

SummaryBackgroundMaternal vitamin D status in pregnancy is a suggested determinant of bone-mineral content (BMC) in offspring, but has been assessed in small studies. We investigated this association in a large prospective study.MethodsEligible participants were mother-and-singleton-offspring pairs who had participated in the Avon Longitudinal Study of Parents and Children, and in which the mother had recorded measurements of 25(OH)D concentration in pregnancy and the offspring had undergone dual-energy x-ray absorptiometry at age 9–10 years. 25(OH)D concentrations in pregnancy were assessed per 10·0 nmol/L and classified as sufficient (more than 50·00 nmol/L), insufficient (49·99–27·50 nmol/L), or deficient (lower than 27·50 nmol/L). Associations between maternal serum 25(OH)D concentrations and offspring total body less head (TBLH) and spinal BMC were assessed by trimester.Results3960 mother-and-offspring pairs, mainly of white European origin, were assessed (TBLH BMC n=3960, spinal BMC n=3196). Mean offspring age was 9·9 years. 2644 (67%) mothers had sufficient, 1096 (28%) insufficient, and 220 (6%) deficient 25(OH)D concentrations in pregnancy, but TBLH and spinal BMC did not differ between offspring of mothers in the lower two groups versus sufficient 25(OH)D concentration. No associations with offspring BMC were found for any trimester, including the third trimester, which is thought to be most relevant (TBLH BMC confounder-adjusted mean difference −0·03 g per 10·0 nmol/L, 95% CI −1·71 to 1·65; spinal BMC 0·04 g per 10·0 nmol/L, 95% CI −0·12 to 0·21).ConclusionsWe found no relevant association between maternal vitamin D status in pregnancy and offspring BMC in late childhood.FundingUK Medical Research Council, Wellcome Trust, and University of Bristol.

Sublethal Exposure to Phosphine Decreases Offspring Production in Strongly Phosphine Resistant Female Red Flour Beetles, Tribolium castaneum (Herbst)

The red flour beetle is a cosmopolitan pest of stored grain and stored grain products. The pest has developed resistance to phosphine, the primary chemical used for its control. The reproductive output of survivors from a phosphine treatment is an important element of resistance development but experimental data are lacking. We exposed mated resistant female beetles to 0.135 mg/L of phosphine for 48 h at 25°C. Following one week of recovery we provided two non-exposed males to half of the phosphine exposed females and to half of the non-exposed control females. Females that had been exposed produced significantly fewer offspring than non-exposed females. Females that remained isolated produced significantly fewer offspring than both exposed females with access to males and non-exposed controls (P<0.05). Some females were permanently damaged from exposure to phosphine and did not reproduce even when given access to males. We also examined the additional effects of starvation prior to phosphine exposure on offspring production. Non-exposed starved females experienced a small reduction in mean offspring production in the week following starvation, followed by a recovery in the second week. Females that were starved and exposed to phosphine demonstrated a very significant reduction in offspring production in the first week following exposure which remained significantly lower than that of starved non-exposed females (P<0.05). These results demonstrate a clear sublethal effect of phosphine acting on the female reproductive system and in some individuals this can lead to permanent reproductive damage. Pest population rebound after a fumigation may be slower than expected which may reduce the rate of phosphine resistance development. The results presented strongly suggest that phosphine resistance models should include sublethal effects.

DNA methylation of peroxisome proliferator-activated receptor γ promoter region and down-regulation of its mRNA expression in liver decrease insulin sensitivity of fetal growth restricted rats

Objective To explore the effect of methylation ot peroxlsome prolllerator-acnvatecl receptor 7 （PPART） gene promoter in liver and its mRNA expression changes on decreasing of insulin sensitivity in feta[ growth restriction （FGR） rats. Methods Twenty pregnant rats were randomly divided into two groups on their first day of pregnancy., normal-protein group （NP） and low-protein group （LP）, ten in each. During pregnancy the LP group rats were fed with low-protein diet （8.00%protein）, while the NP group rats were fed with normal-protein diet （20.00% protein）. The offspring rats were fed with standard feed after 21 days of birth. Male offsprings in NP group were as control offsprings, and male FGR offsprings in LP group ware as FGR offsprings. At day 3, 7, 14, 30, 60 and 90, fasting blood of offsprings was collected to measure fasting plasma glucose （FPG） and fasting insulin（FINS）. Then insulin resistance index of homeostasis model assessment （HOMA 1R） and insulin sensitivity index （ISI） were calculated to evaluate insulin sensitivity. At day 7 and 90, liver tissue of male offsprings was collected to extract DNA and total RNA. The methylation level of PPARy gene promoter and its mRNA expression were detected by methylation specific-polymerase chain reaction （MS-PCR） and reverse transcription-RCR, respectively. The relationships between methylation of PPARy gene promoter and mRNA expression and insulin sensitivity were analyzed by Pearson correlation and nonparametric test method. Results （1） The mean offspring birth-weight of LP group was （4.92±0.36） g, which was lower than that [（6.43±0.59） g] of control group （t= 14.73, P〈0.05）. In LP group, the incidence of FGR offspring was 88.2% （97/110） and the FGR incidence of male ones was 94.1± （48/51）. （2） At day 90, compared with control offsprings, FPG [（8.95±1.83） mmol/L vs （6.21±1.14） mmol/L, t=-3.291, P〈0.05], FINS [（59.57±9.89） mU/Lvs （36.10%7.32） mU/L, 1=-4.916, P〈0.059 and HOMA-IR （0.967±0.297 vs 0. 410±0. 135, t= -4. 472, P〈0.05） of FGR offsprings were significantly higher; while ISI of FGR offspring was lower than that of control offsprings （-3. 043±0. 294 vs 2. 172±0. 354, t=4. 774, P〈0.05）. （3） There was no significant difference in methylation degree of PPAR7 gene promoter in liver between FGR and control offsprings at day 7 （0/8 vs 2/8, Fisher exact test, P〉0. 05）. The methylation degree of PPAR±＇ gene promoter in liver in FGR offsprings was significantly higher than that of control offsprings at day 90 （8/8 vs 2/8, Fisher exact test, P〈0.05）. Compared with control offsprings, PPARy gene mRNA expression level of FGR offsprings decreased significantly at day 90 （43.07±7.51 vs 146.72± 40.66, t=7.09, P〈0.05）. mRNA expression of PPAR7 gene was the lowest in exhaustive methylation offsprings （27.2±1.6）, and then in partial methylation ones （47.3±33.0）, the highest in no methylation ones （144.6±121.2） （P〈0. 05）. （4） The correlation analysis showed that PPARy mRNA expression level negatively correlated to the level of FPG （r =-0. 819）, FINS （r = 0. 906） and HOMA IR （r=- 0. 860）, P〈0.05 respectively but positively correlated to ISI level （r= 0. 947, P〈0. 05）. Conclusions Hypermethylation in promoter region ofPPAR7 gene might inhibit gene transcription, and he involved in the occurrence of insulin resistance in FGR rats. Key words: Fetal growth retadation Insulin resistance ; PPAR gamma ; DNA methylation

The associations between maternal pre-pregnancy body mass index or gestational weight change during pregnancy and body mass index of the child at 3 years of age

To estimate the associations between maternal pre-pregnancy body mass index (BMI) or gestational weight change (GWC) during pregnancy and offspring BMI at 3 years of age, while taking several pre-and postnatal factors into account. The Norwegian Mother and Child Cohort Study is a population-based pregnancy cohort study of women recruited from all geographical areas of Norway. The study includes 31 169 women enrolled between 2000 and 2009 through a postal invitation sent to women at 17-18 weeks of gestation. Data collected from 5898 of the fathers were included. MAIN OUTCOME MESURES: Offspring BMI at 3 years was the main outcome measured in this study. Mean maternal pre-pregnancy BMI was 24.0 kg m(-2) (s.d. 4.1), mean GWC in the first 30 weeks of gestation was 9.0 kg (s.d. 4.1) and mean offspring BMI at 3 years of age was 16.1 kg m(-2) (s.d. 1.5). Both maternal pre-pregnancy BMI and GWC were positively associated with mean offspring BMI at 3 years of age. Pre-pregnancy BMI and GWC also interacted, and the strength of the interaction between these two factors was strongly associated with the increase in offspring BMI among mothers who gained the most weight during pregnancy and had the highest pre-pregnancy BMI. Our findings show that results could be biased by not including pre-pregnant paternal BMI. This large population-based study showed that both maternal pre-pregnancy BMI and GWC were positively associated with mean offspring BMI at 3 years of age.

Maternal Smoking During Pregnancy Predicts Adult Offspring Cardiovascular Risk Factors – Evidence from a Community-Based Large Birth Cohort Study

BackgroundMaternal smoking during pregnancy is associated with offspring obesity. However, little is known about whether maternal smoking in pregnancy predicts other offspring cardiovascular risk factors including waist circumference (WC), waist-hip-ratio (WHR), pulse rate (PR), systolic (SBP), and diastolic blood pressure (DBP).MethodsWe studied a sub-sample of 2038 (50% males) young adults who were born in Brisbane, Australia to investigate the prospective association of maternal smoking during pregnancy with young adult cardiovascular risk factors. We compared offspring mean BMI, WC, WHR, SBP, DBP and PR and the risk of being overweight and obese at 21 years by three mutually exclusive categories of maternal smoking status defined as never smoked, smoked before and/or after pregnancy but not in pregnancy or smoked during pregnancy and other times.ResultsOffspring of mothers who smoked during pregnancy had greater mean BMI, WC, WHR and PR and they were at greater risk of being obese at 21 years compared to offspring of those mothers who never smoked. The mean of these risk factors among those adult offspring whose mothers stopped smoking during pregnancy, but who then smoked at other times in the child's life, were similar to those mothers who never smoked. These results were independent of a range of potential confounding factors.ConclusionThe findings of this study suggest a prospective association of maternal smoking during pregnancy and offspring obesity as well as PR in adulthood, and reinforce the need to persuade pregnant women not to smoke.

Coalescence in the recent past in rapidly growing populations

In a rapidly growing population one expects that two individuals chosen at random from the nth generation are unlikely to be closely related if n is large. In this paper it is shown that for a broad class of rapidly growing populations this is not the case. For a Galton–Watson branching process with an offspring distribution {pj} such that p0=0 and ψ(x)=∑jpjI{j≥x} is asymptotic to x−αL(x) as x→∞ where L(⋅) is slowly varying at ∞ and 0<α<1 (and hence the mean m=∑jpj=∞) it is shown that if Xn is the generation number of the coalescence of the lines of descent backwards in time of two randomly chosen individuals from the nth generation then n−Xn converges in distribution to a proper distribution supported by N={1,2,3,…}. That is, in such a rapidly growing population coalescence occurs in the recent past rather than the remote past. We do show that if the offspring mean m satisfies 1<m≡∑jpj<∞ and p0=0 then coalescence time Xn does converge to a proper distribution as n→∞, i.e., coalescence does take place in the remote past.

Conditional Least Squares Estimators for the Offspring Mean in a Subcritical Branching Process with Immigration

Consider a Bienayme–Galton–Watson process with generation-dependent immigration, whose mean and variance vary regularly with non negative exponents α and β, respectively. We study the estimation problem of the offspring mean based on an observation of population sizes. We show that if β <2α, the conditional least squares estimator (CLSE) is strongly consistent. Conditions which are sufficient for the CLSE to be asymptotically normal will also be derived. The rate of convergence is faster than n −1/2, which is not the case in the process with stationary immigration.

Diffusion Approximation of an Array of Controlled Branching Processes

In this paper an array of controlled branching processes is considered. Using operator semigroup convergence theorems, it is proved that the fluctuation limit is a diffusion process under the conditions that the offspring and control means tend to be critical. As an application of this result, in a parametric framework, it is obtained that the bootstrapping distribution of the weighted conditional least squares estimator of the offspring mean in the critical case is not consistent. From this, it is concluded that the standard parametric bootstrap weighted conditional least squares estimate is asymptotically invalid in the critical case.

Effects of a high maternal sodium intake on offspring of genetically diverse (CCHS) mice

The present study sought to determine whether a high maternal salt intake during pregnancy and lactation affected offspring blood pressure (BP), heart rate (HR), or locomotor activity in a genetically diverse stock of mice (Collaborative Cross Heterozygous Stock, CCHS). Dams were fed a low or high salt diet (0.25% NaCl (LS) vs 5% NaCl (HS)) from before conception through weaning, and telemetry studies were performed in 10 month old male offspring raised on either the LS or HS diet. A maternal HS diet was associated with significantly smaller litter sizes (P=0.03, data from groups of 34 and 37 litters), but offspring weight was not affected at any time between the day of birth (data from 22 and 24 litters) and 10 months of age (group sizes ≥ 11). Telemetry studies revealed no effects of maternal HS on mean BP or HR. However, maternal HS was associated with increased circadian variation in BP, increased percentage of time spent active during the 12h light period, and a tendency towards increased pulse pressure (P=0.03, 0.04, 0.06, respectively, group sizes of 8 – 14). Our results indicate that a maternal high salt diet does not affect offspring mean BP level in 10 month old male CCHS mice, but does reduce litter size and has subtle effects on activity and blood pressure cycles. Supported by the Canadian Institutes of Health Research (#91547).

Gestational Weight Gain and Body Mass Index in Children: Results from Three German Cohort Studies

IntroductionPrevious studies suggested potential priming effects of gestational weight gain (GWG) on offspring’s body composition in later life. However, consistency of these effects in normal weight, overweight and obese mothers is less clear.MethodsWe combined the individual data of three German cohorts and assessed associations of total and excessive GWG (as defined by criteria of the Institute of Medicine) with offspring’s mean body mass index (BMI) standard deviation scores (SDS) and overweight at the age of 5–6 years (total: n = 6,254). Quantile regression was used to examine potentially different effects on different parts of the BMI SDS distribution. All models were adjusted for birth weight, maternal age and maternal smoking during pregnancy and stratified by maternal pre-pregnancy weight status.ResultsIn adjusted models, positive associations of total and excessive GWG with mean BMI SDS and overweight were observed only in children of non- overweight mothers. For example, excessive GWG was associated with a mean increase of 0.08 (95% CI: 0.01, 0.15) units of BMI SDS (0.13 (0.02, 0.24) kg/m2 of ‘real’ BMI) in children of normal-weight mothers. The effects of total and excessive GWG on BMI SDS increased for higher- BMI children of normal-weight mothers.DiscussionIncreased GWG is likely to be associated with overweight in offspring of non-overweight mothers.

Bayesian estimation of the offspring mean in branching processes: Application to infectious disease data

A single-type Bienaymé–Galton–Watson branching process (BGWBP) with a generalized power series offspring distribution is considered as a model of the spread of an infectious disease in a population. Our main goal is to estimate the basic reproduction number R0, which is represented by the offspring mean of the BGWBP, applying a Bayesian approach. The only data assumed to be available are the initial number of infected individuals and the total number of infected individuals. We are using the Metropolis–Hastings algorithm to simulate the posterior distribution. The usefulness of the described method is demonstrated on some real data on the number of reported cases of mumps in Bulgaria during the period 2005–2008.

Inheritance of Maize Prolificacy under High Plant Density

The strong association of prolificacy in maize with tolerance to high plant density reported in the literature by many investigators has stimulated us to study the inheritance and expression of such trait under high and low plant densities. A diallel cross among eight diverse inbred lines in number of ears plant -1 was performed in 2010 season and the resulting F1’s along with their parental lines were evaluated in 2011 season under two plant densities (20,000 and 40,000 plants fed -1 ) using a split plot design in randomized complete blocks (RCB) arrangement with three replications at two locations (Bani Sweif and Minufiya). The main objective was to obtain information on the expression of genes controlling maize prolificacy under low and high plant density. Analyses of variance indicated existence of significant differences among locations, plant densities and genotypes for all studied traits. Performance of inbred lines and F1 crosses vary with location and plant density. Parental lines L14, L17, L18 and L53 were the best in mean performance and general combining ability effects (GCA) for ears plant -1 (EPP), grain yield plant -1 (GYPP) and grain yield fed -1 (GYPF) under high and low densities. The best F1 crosses in mean performance and specific combining ability effects (SCA) under high-density were L14×L17, L14×L18 and L18×L20 for EPP and L14×L17, L18×L20 and L18×L55 for EPP and GYPP. Type of dominance controlling inheritance of EPP trait changed from complete dominance to the prolific parent under low density to complete dominance to the non-prolific parent under high density. Results indicated that to obtain a hybrid of high EPP and GYPP under high-density, at least one of its parents should be prolific, but to obtain a hybrid of high GYPF, both of its parents should be prolific. The magnitude of genetic variance (additive and dominance) and heritability in narrow-sense for the three traits EPP, GYPP and GYPF was lower under high-density than that under low-density. Both additive and dominance variances were highly significant for the three traits, but the magnitude of dominance was higher than that of additive variance. Results confirm the simple inheritance of EPP trait (one gene) as reported by some investigators under high and low density. Prolificacy may be rapidly transferred from a prolific exotic inbred to the non-prolific Egyptian inbreds used in commercial hybrids by a conversion backcrossing program. Expected genetic advance (GA) from selection ranged from 9.49% for high EPP to 22.66% for GYPP under highdensity. Estimates of GA were higher under low than under high-density, indicating that selection for high EPP is more efficient than under low-density. Correlation coefficients for means vs. GCA effects of inbreds, means vs. heterobeltiosis, means vs. SCA effects and SCA effects vs. heterobeltiosis of F1 crosses as well as parents means vs. offspring means and breeding values were estimated and discussed.

Secondary Sex Ratios in Six Snake Species

Sex ratios at birth or hatching in snake populations are often assumed to be 1∶1 in agreement with Fisherian theory. We evaluated secondary sex ratios (SSRs) in two viperids (Sistrurus catenatus and S. miliarius) and four natricine colubrids (Nerodia rhombifer, Thamnophis proximus, T. radix, and T. sirtalis). We captured 274 gravid females that produced 2443 living offspring. Population-level SSRs in our focal species did not differ significantly from 1∶1. In addition, variation in individual litter SSRs conformed to expectations generated by the binomial distribution with an even sex ratio. Each species showed individual variation in SSRs; however, the majority of variation in litter SSRs was not explained by variation in the maternal or litter characteristics we examined. The three exceptions were a very strong negative association between mean offspring mass and litter SSR in T. radix (r2 = 0.96), a strong positive association between mean offspring mass and litter sex ratio in T. proximus (r2 = 0.40), and a strong positive association between maternal condition and litter SSR in T. proximus (r2 = 0.40). Whether or not these relationships have functional or adaptive significance warrants further study. The majority of our results were unsurprising and not statistically significant. We suggest, however, that the presentation and publication of both non-significant and significant results is exactly what is needed to give an accurate view of SSRs at both the population level and the maternal level in snakes.

Asymptotic inference for partially observed branching processes

We consider the problem of estimation in a partially observed discrete-time Galton-Watson branching process, focusing on the first two moments of the offspring distribution. Our study is motivated by modelling the counts of new cases at the onset of a stochastic epidemic, allowing for the facts that only a part of the cases is detected, and that the detection mechanism may affect the evolution of the epidemic. In this setting, the offspring mean is closely related to the spreading potential of the disease, while the second moment is connected to the variability of the mean estimators. Inference for branching processes is known for its nonstandard characteristics, as compared with classical inference. When, in addition, the true process cannot be directly observed, the problem of inference suffers significant further perturbations. We propose nonparametric estimators related to those used when the underlying process is fully observed, but suitably modified to take into account the intricate dependence structure induced by the partial observation and the interaction scheme. We show consistency, derive the limiting laws of the estimators, and construct asymptotic confidence intervals, all valid conditionally on the explosion set.

Asymptotic inference for partially observed branching processes

We consider the problem of estimation in a partially observed discrete-time Galton-Watson branching process, focusing on the first two moments of the offspring distribution. Our study is motivated by modelling the counts of new cases at the onset of a stochastic epidemic, allowing for the facts that only a part of the cases is detected, and that the detection mechanism may affect the evolution of the epidemic. In this setting, the offspring mean is closely related to the spreading potential of the disease, while the second moment is connected to the variability of the mean estimators. Inference for branching processes is known for its nonstandard characteristics, as compared with classical inference. When, in addition, the true process cannot be directly observed, the problem of inference suffers significant further perturbations. We propose nonparametric estimators related to those used when the underlying process is fully observed, but suitably modified to take into account the intricate dependence structure induced by the partial observation and the interaction scheme. We show consistency, derive the limiting laws of the estimators, and construct asymptotic confidence intervals, all valid conditionally on the explosion set.

Direct and indirect transmission of relationship functioning across generations.

Relationship functioning is assumed to propagate across subsequent generations, but most studies have lacked appropriate methodologies to test this assumption prospectively. In a randomly selected sample of youth (N = 821) followed prospectively for over 25 years across multiple generations, we examined the association of romantic engagement (i.e., emotional involvement and closeness) between parents with offspring romantic relationship quality. We tested two developmental pathways linking parents' romantic engagement with offspring adult romantic relationship quality, the first operating via parenting practices, and the second operating via adolescent depression. Parents' romantic engagement predicted offspring romantic relationship quality a mean of 17 years later, net age and socioeconomic status. Results supported a developmental pathway from parents' romantic engagement at offspring mean age 14, to parenting at offspring mean age 16, to offspring socioemotional functioning at mean age 22, and offspring romantic relationship quality at mean age 33. However, the influence of parents' romantic engagement on offsprings' adult romantic relationship quality does not appear to operate via a pathway of adolescent depression. Implications for prevention are discussed.

A Note on Estimation of Parameters for Branching Processes with Immigration

It is proved that under certain conditions the conditional least-squares estimator of the offspring mean for a sequence of nearly critical Jiřina processes with immigration is consistent but not asymptotically normal and the conditional least-squares estimator of the immigration mean is not consistent. These results differ from the existing results in the case where the initial values are zero (see Ispány et al., 2005).

Educational Homogamy Lowers the Odds of Reproductive Failure

Assortative mating based on education is a common phenomenon. We investigated whether it affected parameters of reproductive performance such as childlessness, offspring number and age at first marriage. On the basis of the US census from 1980 (n = 670,631 married US couples), we find that the proportion of childless individuals is usually minimal in women married to a husband of the same educational level. This holds particularly true in the highest and the lowest educated women. Educational homogamy is also associated with a lower average age at first marriage. No obvious effect of educational homogamy on a woman's average offspring number is found, where mean offspring number generally increases both with decreasing woman's and decreasing husband's educational attainment. We conclude that educational homogamy reduces the likelihood of reproductive failure.

The diabetic pregnancy and offspring BMI in childhood: a systematic review and meta-analysis

Offspring of mothers with diabetes are at increased risk of metabolic disorders in later life. Increased offspring BMI is a plausible mediator. We performed a systematic review and meta-analysis of studies examining offspring BMI z score in childhood in relation to maternal diabetes. Papers reporting BMI z scores for offspring of diabetic (all types, and pre- and during-pregnancy onset) and non-diabetic mothers were included. Citations were identified in PubMed; bibliographies of relevant articles were hand-searched and authors contacted for additional data where necessary. We compared offspring BMI z score with and without adjustment for maternal pre-pregnancy BMI. We performed fixed effect meta-analysis except where significant heterogeneity called for use of a random effects analysis. Data were available from nine studies. In the diabetic group unadjusted mean offspring BMI z score was 0.28 higher (all diabetic mothers vs controls (95% CI 0.09, 0.47; p = 0.004; nine studies; offspring of diabetic mothers n = 927, controls n = 26,384) and with adjustment for maternal pre-pregnancy BMI, 0.07 higher (95% CI -0.15, 0.28; p = 0.54; three studies; offspring of diabetic mothers n = 244, controls n = 11,206). There was no evidence of a difference in offspring BMI z score in relation to type of diabetes (gestational vs type 1, p = 0.95). Maternal diabetes is associated with increased offspring BMI z score, although this is no longer apparent after adjustment for maternal pre-pregnancy BMI in the limited number of studies in which this is reported. Causal mediators of the effect of maternal diabetes on offspring outcomes remain to be established; we recommend that future research includes adjustment for maternal pre-pregnancy BMI.

Perinatal winter conditions affect later reproductive performance in romanian women: Intra and intergenerational effects

To compare epidemiological studies on Austrian and New Zealand women that report below average reproductive performance after birth in summer, with a similar study in Romanian women. We examined the association between birth month and offspring count analyzing census data from Romania obtained from IPUMS International (Population and Housing Census of Romania, year 2002), totaling 411,270 women aged older than 45 years. We investigated whether socio-economic status affected this association, and whether intergenerational effects exist for mother's birth month in relation to their daughter's offspring number. The time series of mean offspring count per birth month has a highly significant period of 12 months. Contrary to our expectations, average offspring count is highest in women born in June and lowest in those born in December, with a strong coincidence between negative peak values of residuals of mean offspring count per birth month and corresponding monthly means of ambient temperature in Romania. The association between winter birth and lower offspring number is significant in poorly educated women only. For mothers born in winter there is also an association with a lower daughters' offspring count. Conflicting results exist between Romania and Austria/New Zealand, and may be most easily explained by women's different exposure to winter conditions in these countries.