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How many cubs can a mum nurse? Maternal age and size influence litter size in polar bears.

ABSTRACT: Life-history theory predicts that females' age and size affect the level of maternal investment in current reproduction, balanced against the future reproductive effort, maintenance and survival. Using long-term (30 years) individual data on 193 female polar bears ( Ursus maritimus), we assessed age- and size-specific variation on litter size. Litter size varied with maternal age, younger females had higher chances of losing a cub during their first months of life. Results suggest an improvement in reproductive abilities early in life due to experience with subsequent reproductive senescence. Litter size increased with maternal size, indicating that size may reflect individual quality. We also found an optimum in the probability of having twins, suggesting stabilizing selection on female body size. Heterogeneity was observed among the largest females, suggesting that large size comes at a cost.

SUBMITTER: Folio DM

PROVIDER: S-EPMC6548740 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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How many cubs can a mum nurse? Maternal age and size influence litter size in polar bears.

Folio Dorinda Marie DM Aars Jon J Gimenez Olivier O Derocher Andrew E AE Wiig Øystein Ø Cubaynes Sarah S

Biology letters 20190501 5

Life-history theory predicts that females' age and size affect the level of maternal investment in current reproduction, balanced against the future reproductive effort, maintenance and survival. Using long-term (30 years) individual data on 193 female polar bears ( Ursus maritimus), we assessed age- and size-specific variation on litter size. Litter size varied with maternal age, younger females had higher chances of losing a cub during their first months of life. Results suggest an improvement ...[more]

PMID: 31039729

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Project description:ObjectivesTo investigate associations between maternal body mass index (BMI) at delivery (using pregnancy-specific BMI cut-off values 5?kg/m2 higher in each of the WHO groups) and clinical, theatre utilisation and health economic outcomes for women undergoing caesarean section (CS).DesignA prospective multicentre observational study.SettingSeven secondary or tertiary referral obstetric hospitals.ParticipantsOne thousand and four hundred and fifty-seven women undergoing all categories of CS.Data collectionHeight and weight were recorded at the initial antenatal visit and at delivery. We analysed the associations between delivery BMI (continuous and pregnancy-specific cut-off values) and total theatre time, surgical time, anaesthesia time, maternal and neonatal adverse outcomes, total hospital admission and theatre costs.ResultsMean participant characteristics were: age 32 years, gestation at delivery 38.4 weeks and delivery BMI 32.2?kg/m2. Fifty-five per cent of participants were overweight, obese or super-obese using delivery pregnancy-specific BMI cut-off values. As BMI increased, total theatre time, surgical time and anaesthesia time increased. Super-obese participants had approximately 27% (17 min, p<0.001) longer total theatre time, 20% (9 min, p<0.001), longer surgical time and 40% (11 min, p<0.001) longer anaesthesia time when compared with normal BMI participants. Increased BMI at delivery was associated with increased risk of maternal intensive care unit admission (relative risk 1.07, p=0.045), but no increased risk of neonatal admission to higher acuity care. Total hospital admission costs were 15% higher in super-obese women compared with normal BMI women and theatre costs were 27% higher in super-obese women.ConclusionsIncreased maternal BMI was associated with increased total theatre time, surgical and anaesthesia time, increased total hospital admission costs and theatre costs. Clinicians and health administrators should consider these clinical risks, time implications and financial costs when managing pregnant women.

Dataset Information

How many cubs can a mum nurse? Maternal age and size influence litter size in polar bears.

Publications

How many cubs can a mum nurse? Maternal age and size influence litter size in polar bears.

Similar Datasets

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