Maternal Effort Research Articles

Are Females Maternal Manipulators, Selfish Mothers, Or Both? Insight from Pythons

Abstract During reproduction, females often modify their behavior relative to the nonreproductive condition. These changes are frequently attributed to maternal efforts to optimize offspring development and survival (i.e., the maternal manipulation hypothesis). However, Schwarzkopf and Andrews (2012) recently challenged this concept as oversimplified, emphasizing that females should optimize their own lifetime fitness, and therefore maternal efforts may be directed at the female's future reproductive effort in addition, or even in contrast, to current reproductive effort. To provide insight into the relative importance of current versus future reproductive effort in shaping maternal behavior, we systematically explore a single study system—pythons. Pythons show distinct maternal behaviors during gravidity (modified basking effort), peri-oviposition (nest site selection), and postoviposition (egg brooding). By examining each component, we reveal that python maternal effort is predominantly aimed at current...

Active Management of the Third Stage of Labour With and Without Controlled Cord Traction

Summary Background Active management of the third stage of labour reduces the risk of post-partum haemorrhage. We aimed to assess whether controlled cord traction can be omitted from active management of this stage without increasing the risk of severe haemorrhage. Methods We did a multicentre, non-inferiority, randomised controlled trial in 16 hospitals and two primary health-care centres in Argentina, Egypt, India, Kenya, the Philippines, South Africa, Thailand, and Uganda. Women expecting to deliver singleton babies vaginally (ie, not planned caesarean section) were randomly assigned (in a 1:1 ratio) with a centrally generated allocation sequence, stratified by country, to placental delivery with gravity and maternal effort (simplified package) or controlled cord traction applied immediately after uterine contraction and cord clamping (full package). After randomisation, allocation could not be concealed from investigators, participants, or assessors. Oxytocin 10 IU was administered immediately after birth with cord clamping after 1–3 min. Uterine massage was done after placental delivery according to local policy. The primary (non-inferiority) outcome was blood loss of 1000 mL or more (severe haemorrhage). The non-inferiority margin for the risk ratio was 1·3. Analysis was by modified intention-to-treat, excluding women who had emergency caesarean sections. This trial is registered with the Australian and New Zealand Clinical Trials Registry, ACTRN 12608000434392. Findings Between June 1, 2009, and Oct 30, 2010, 12 227 women were randomly assigned to the simplified package group and 12 163 to the full package group. After exclusion of women who had emergency caesarean sections, 11 861 were in the simplified package group and 11 820 were in the full package group. The primary outcome of blood loss of 1000 mL or more had a risk ratio of 1·09 (95% CI 0·91–1·31) and the upper 95% CI limit crossed the pre-stated non-inferiority margin. One case of uterine inversion occurred in the full package group. Other adverse events were haemorrhage-related. Interpretation Although the hypothesis of non-inferiority was not met, omission of controlled cord traction has very little effect on the risk of severe haemorrhage. Scaling up of haemorrhage prevention programmes for non-hospital settings can safely focus on use of oxytocin. Funding United States Agency for International Development and UN Development Programme/UN Population Fund/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research.

Avian eggshell pigments are not consistently correlated with colour measurements or egg constituents in two Turdus thrushes

The colourful appearance of avian eggshells is a prominent aspect of maternal reproductive effort in birds. Some differences in eggshell coloration have been reported to co‐vary with various measures of maternal condition and these patterns support the hypothesis that, in some bird species, several aspects of eggshell colour (i.e. primary chroma and brightness) function as a signal of maternal and offspring quality to induce greater paternal investment. We directly quantified eggshell pigment concentrations of blackbird Turdus merula and song thrush T. philomelos eggshells and tested how the two key pigments (protoporphyrin IX and biliverdin) co‐varied with other eggshell traits and egg constituents as measures of maternal reproductive investment, including total yolk carotenoid concentration, total lipid concentration, yolk mass, and shell thickness. Contrary to predictions, we detected few statistical patterns overall. We found that protoporphyrin IX concentration was negatively associated with blue‐green chroma in blackbirds but not in song thrush. The concentration of protoporphyrin IX was significantly greater in blackbirds and also showed different patterns of association with total yolk lipids and yolk carotenoid concentrations between these two species (significant species interaction terms). Our results reveal that it is not appropriate to simply assume in these two avian species that reflectance‐based eggshell colour measures are a suitable proxy for eggshell pigment concentrations or can be used as consistent predictors of maternal reproductive investment. These results highlight the need to assess and validate the strength and direction of the statistical relationships between eggshell colour measures, pigment concentrations, and maternal resource deposition in the egg for other species of birds.

Habitat and life history differences between two species of Gambusia

Life history strategies reflect trade-offs that tend to maximize fitness, such as investment in a few large or many small offspring. We compared life histories of two temperate livebearing fishes Gambusia affinis and G. nobilis, an endangered species which is virtually unstudied. The two species persist in environments that differ widely in abiotic and biotic factors in the same local area. Gambusia affinis were typically found in habitats with high productivity and wide fluctuations in temperature, salinity and dissolved oxygen, whereas G. nobilis occurred in more stable spring-fed habitats. We collected data on life-history traits: embryo mass, brood size (number of embryos), total maternal reproductive effort, population sex ratios, and size (mass and length) distributions of adults and juveniles. There was no difference between species in reproductive effort per brood, but they differed in investment strategy. Gambusia affinis females produced large broods with small embryos, whereas G. nobilis females produced broods of fewer, larger embryos. These differences in life history strategies reflect a tradeoff between individual productivity and differential mortality rates in different environments. At our field site G. affinis persists as an annual species with relatively high growth rates and corresponding reproductive patterns, whereas G. nobilis females have a slower reproductive tempo and may live multiple years.

Dynamic Influence of Maternal and Pup Traits on Maternal Care during Lactation in an Income Breeder, the Antarctic Fur Seal

Life-history theory predicts that selection will favor optimal levels of parental effort that balance benefits of current reproduction with costs to survival and future reproduction. The optimal level of effort depends on parental traits, offspring traits, and provisioning strategy. Additionally, how these factors influence effort may differ depending on the stage of reproduction. The relative importance of maternal and offspring traits on energy allocation to offspring was investigated in known-age Antarctic fur seals Arctocephalus gazella across four stages of reproduction, using birth mass and milk-consumption measurements. Maternal traits were important during three of the four stages investigated, with larger females giving birth to larger pups and investing more in pups during perinatal and molt stages. Pup mass influenced maternal effort during the premolt stage, and provisioning strategy influenced postnatal maternal effort at all stages. Energy provided to the offspring during an attendance visit was positively related to the duration of the foraging-trip/visit cycle; however, when investment was controlled for trip/visit cycle duration, the overall rate of energy transfer was similar across trip durations. In addition to strong effects of maternal mass, pup traits affected energy allocation, suggesting that pup demand is important in determining maternal care. These findings emphasize the importance of considering state variables in life-history studies and suggest that timing of measurements of effort in species with long provisioning periods may influence conclusions and our ability to make comparisons of reproductive effort among species.

Management of a pregnancy with underlying fibromuscular dysplasia with a history of stroke and carotid artery dissection

Fibromuscular dysplasia is a non-inflammatory angiopathy that occurs predominately in young to middle-aged females,2 affecting most commonly the renal (60-75%) and cerviocranial (25-30%) arteries.2 During pregnancy and the puerperium the...

Active management of the third stage of labour with and without controlled cord traction: a randomised, controlled, non-inferiority trial

Active management of the third stage of labour reduces the risk of post-partum haemorrhage. We aimed to assess whether controlled cord traction can be omitted from active management of this stage without increasing the risk of severe haemorrhage. We did a multicentre, non-inferiority, randomised controlled trial in 16 hospitals and two primary health-care centres in Argentina, Egypt, India, Kenya, the Philippines, South Africa, Thailand, and Uganda. Women expecting to deliver singleton babies vaginally (ie, not planned caesarean section) were randomly assigned (in a 1:1 ratio) with a centrally generated allocation sequence, stratified by country, to placental delivery with gravity and maternal effort (simplified package) or controlled cord traction applied immediately after uterine contraction and cord clamping (full package). After randomisation, allocation could not be concealed from investigators, participants, or assessors. Oxytocin 10 IU was administered immediately after birth with cord clamping after 1-3 min. Uterine massage was done after placental delivery according to local policy. The primary (non-inferiority) outcome was blood loss of 1000 mL or more (severe haemorrhage). The non-inferiority margin for the risk ratio was 1·3. Analysis was by modified intention-to-treat, excluding women who had emergency caesarean sections. This trial is registered with the Australian and New Zealand Clinical Trials Registry, ACTRN 12608000434392. Between June 1, 2009, and Oct 30, 2010, 12,227 women were randomly assigned to the simplified package group and 12,163 to the full package group. After exclusion of women who had emergency caesarean sections, 11,861 were in the simplified package group and 11,820 were in the full package group. The primary outcome of blood loss of 1000 mL or more had a risk ratio of 1·09 (95% CI 0·91-1·31) and the upper 95% CI limit crossed the pre-stated non-inferiority margin. One case of uterine inversion occurred in the full package group. Other adverse events were haemorrhage-related. Although the hypothesis of non-inferiority was not met, omission of controlled cord traction has very little effect on the risk of severe haemorrhage. Scaling up of haemorrhage prevention programmes for non-hospital settings can safely focus on use of oxytocin. United States Agency for International Development and UN Development Programme/UN Population Fund/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research.

A Bayesian hierarchical model of Antarctic fur seal foraging and pup growth related to sea ice and prey abundance

We created a Bayesian hierarchical model (BHM) to investigate ecosystem relationships between the physical ecosystem (sea ice extent), a prey measure (krill density), predator behaviors (diving and foraging effort of female Antarctic fur seals, Arctocephalus gazella, with pups) and predator characteristics (mass of maternal fur seals and pups). We collected data on Antarctic fur seals from 1987/1988 to 1994/1995 at Seal Island, Antarctica. The BHM allowed us to link together predators and prey into a model that uses all the data efficiently and accounts for major sources of uncertainty. Based on the literature, we made hypotheses about the relationships in the model, which we compared with the model outcome after fitting the BHM. For each BHM parameter, we calculated the mean of the posterior density and the 95% credible interval. Our model confirmed others' findings that increased sea ice was related to increased krill density. Higher krill density led to reduced dive intensity of maternal fur seals, as measured by dive depth and duration, and to less time spent foraging by maternal fur seals. Heavier maternal fur seals and lower maternal foraging effort resulted in heavier pups at 22 d. No relationship was found between krill density and maternal mass, or between maternal mass and foraging effort on pup growth rates between 22 and 85 days of age. Maternal mass may have reflected environmental conditions prior to the pup provisioning season, rather than summer prey densities. Maternal mass and foraging effort were not related to pup growth rates between 22 and 85 d, possibly indicating that food was not limiting, food sources other than krill were being used, or differences occurred before pups reached age 22 d.

Effect of mate size on maternal reproductive effort in the convict cichlid Amatitlania siquia

Abstract The differential allocation hypothesis predicts individuals will increase their reproductive investment when mated to a high quality partner. In many species of fish with biparental care females prefer large males due to the males’ greater ability to raise more offspring to independence. I examined the relationship between mate quality, parental care and number of offspring in a natural population of convict cichlids Amatitlania siquia. The frequency of frontal displays by females was positively correlated with male standard length. Additionally, as males increased in length relative to their mate, females increased the frequency of chases towards predators, while males decreased the number of displays towards brood predators. This trade-off in parental effort within a pair due to mate quality is a key prediction of differential allocation. The number of offspring was correlated with male, but not female, standard length. These results support the differential allocation hypothesis in that females offered more parental care to offspring of a larger male, while their mates decreased the amount of care they provided. Additionally, females benefited in terms of number of offspring by pairing with higher quality mates. Increased female investment may provide an incentive to ensure male care and maintain pair bonding, which could lead to greater reproductive success through increased offspring survival.

Monitoring Human Development Goals: A Straightforward (Bayesian) Methodology for Cross-National Indices

We offer a straightforward framework for measurement of progress, across many dimensions, using cross-national social indices, which we classify as linear combinations of multivariate country level data onto a univariate score. We suggest a Bayesian approach which yields probabilistic (confidence type) intervals for the point estimates of country scores—a vital, and often missing, feature in cross-national comparisons. We demonstrate our approach using the United Nations Development Programme’s Millennium Development Goals (MDGs), via the Maternal and Neonatal Program Effort Index (MNPI) data (Ross et al. in Trop Med Inter Health 6(10):787–798, 2001), and Human Development Index (HDI) (2010) as examples.

Irish and New Zealand midwives' expertise in expectant management of the third stage of labour: The ‘MEET’ study

Objectiveto explore the views of expert midwives in Ireland and New Zealand of the skills they employ in expectant management of the third stage of labour (EMTSL). Designuniversity ethical approval was granted for a qualitative descriptive study in 2010. Recorded, semi-structured interviews were undertaken. Constant comparative analysis was used. Settingcommunity birth settings in Ireland and New Zealand. Participants27 consenting midwives who used EMTSL in at least 30% of births, with PPH rates less than 4%. Findingsthe majority of respondents believed the third stage was a special time of parent–baby discovery and ‘watchful waiting’, with no intervention necessary. Great importance was placed on women's feelings, behaviour and a calm environment. Skin-to-skin contact, breast feeding, not clamping the cord, upright positions and maternal effort, sometimes assisted by gentle cord-traction were also used. Key conclusionssome components of EMTSL identified by these expert midwives are not recorded in text-books, but are based on experience and expertise. These elements of EMTSL add to midwifery knowledge and provide a basis for further discussion on how normal physiology can be supported during the third stage. Implications for practiceuse of these elements is recommended for women who request EMTSL, and for those in countries without ready access to uterotonics.

Do maternal food deprivation and offspring predator cues interactively affect maternal effort in fish?

The state of the environment parents are exposed to during reproduction can either facilitate or impair their ability to take care of their young. Thus, the environmental conditions experienced by parents can have a transgenerational impact on offspring phenotype and survival. Parental energetic needs and the variance in offspring predation risk have both been recognized as important factors influencing the quality and amount of parental care, but surprisingly, they are rarely manipulated simultaneously to investigate how parents adjust care to these potentially conflicting demands. In the maternally mouthbrooding cichlid Simochromis pleurospilus, we manipulated female body condition before spawning and exposure to offspring predator cues during brood care in a two-by-two factorial experiment. Subsequently, we measured the duration of brood care and the number and size of the released young. Furthermore, we stimulated females to take up their young by staged predator attacks and recorded the time before the young were released again. We found that food-deprived females produced smaller young and engaged less in brood care behaviour than well-nourished females. Final brood size and, related to this, female protective behaviour were interactively determined by nutritional state and predator exposure: well-nourished females without a predator encounter had smaller broods than all other females and at the same time were least likely to take up their young after a simulated predator attack. We discuss several mechanisms by which predator exposure and maternal nutrition might have influenced brood and offspring size. Our results highlight the importance to investigate the selective forces on parents and offspring in combination, if we aim to understand reproductive strategies.

Operative Vaginal Delivery

Operative vaginal delivery remains a valid option when problems arise in the second stage of labor. The most common indications are fetal compromise and failure to deliver spontaneously with maximum maternal effort. There is a clear trend to choose vacuum extraction over forceps to assist delivery, but the evidence supporting that trend is unconvincing. Recent literature confirms some advantages for forceps (eg, a lower failure rate) and some disadvantages for vacuum extraction (eg, increased neonatal injury), depending on the clinical circumstances. To preserve the option of forceps delivery, residency training programs must incorporate detailed instruction in forceps techniques and related skills into their curricula. Simulation training can enhance residents' understanding of mechanical principles and should logically precede clinical work.

Rising rate of second stage C-section: who is to blame? A questionnaire based study of trainees in the North East of England

Second stage Caesarean section as a result of failed operative delivery is increasing. This may partly be due to inadequate training and wrong choice of instrument. Our aim was to...

Maternal care and infant development in Callimico goeldii and Callithrix jacchus

Callimico goeldii gives birth to single offspring, whereas other callitrichids, including Callithrix jacchus, twin. This study compares maternal effort and infant development in C. goeldii and C. jacchus; it is the first study to look at nursing frequency. Infants were observed from birth for 7 weeks in two captive groups each of C. goeldii and C. jacchus. C. goeldii mothers physiologically invested the same or less than C. jacchus mothers. C. goeldii mothers gained the same amount of weight during pregnancy in absolute terms as did the smaller C. jacchus. This results in a smaller gain in proportion to maternal weight but an equivalent proportional gain on a per fetus basis. C. goeldii mothers nursed their infants less based on duration of nursing bouts compared with C. jacchus mothers. C. goeldii mothers transported their infants exclusively through the first 2 weeks of life, which is longer than C. jacchus mothers, who exclusively transported infants only during the first week of life. As maternal infant carriage declined, other group members transported offspring in both species. C. goeldii infants engaged in independent locomotive sequences later in development and tasted solid foods less frequently than C. jacchus infants when compared at equivalent ages. A single, opportunistic milk sample obtained from a C. goeldii mother when her infant was 48 days old indicates that C. goeldii milk contains gross energy from crude protein within the range of variation observed in Callithrix milk. Despite the similarities in milk quality and prenatal effort in individual fetuses, C. goeldii infants gain weight faster from 0 to 18 months than do C. jacchus infants. A reduction in litter size allows C. goeldii mothers to spend more time carrying their infant and to delay weaning, thereby allowing accelerated infant and juvenile growth rates compared with C. jacchus.

Terminal investment and senescence in rhesus macaques (Macaca mulatta) on Cayo Santiago.

Long-lived iteroparous species often show aging-related changes in reproduction that may be explained by 2 non-mutually exclusive hypotheses. The terminal investment hypothesis predicts increased female reproductive effort toward the end of the life span, as individuals have little to gain by reserving effort for the future. The senescence hypothesis predicts decreased female reproductive output toward the end of the life span due to an age-related decline in body condition. Nonhuman primates are ideal organisms for testing these hypotheses, as they are long lived and produce altricial offspring heavily dependent on maternal investment. In this study, we integrated 50 years of continuous demographic records for the Cayo Santiago rhesus macaque (Macaca mulatta) population with new morphometric and behavioral data to test the senescence and terminal investment hypotheses. We examined relationships between maternal age and activity, mother and infant body condition, interbirth intervals, measures of behavioral investment in offspring, and offspring survival and fitness to test for age-associated declines in reproduction that would indicate senescence, and for age-associated increases in maternal effort that would indicate terminal investment. Compared with younger mothers, older mothers had lower body mass indices and were less active, had longer interbirth intervals, and spent more time in contact with infants, but had infants of lower masses and survival rates. Taken together, our results provide strong evidence for the occurrence of reproductive senescence in free-ranging female rhesus macaques but are also consistent with some of the predictions of the terminal investment hypothesis.

Secondary sex ratios do not support maternal manipulation: extensive data from laboratory colonies of spiny mice (Muridae: Acomys)

Spiny mice of the genus Acomys (Muridae) represent a very suitable mammalian model for studying factors influencing the secondary sex ratio (SSR). The maternal effort in these rodents is extremely biased in favour of the prenatal period and, therefore, maternal manipulation of the SSR is potentially more advantageous. We studied the SSR in four populations/species of spiny mice kept in family groups consisting of two closely related females, one non-relative male and their descendants. The groups were established from founding animals aged about 3 months (maturing age) and were allowed to breed freely for several months. Each litter was sexed after birth, and relevant data were thoroughly recorded. Altogether, data were collected on 1684 litters: 189 of Acomys sp. from Iran, 203 of A. cilicicus, 875 of A. cahirinus, and 417 of A. dimidiatus. We recorded the sex of 4048 newborns of which 1995 were males and 2053 were females. The overall sex ratio was close to 1:1 (49.2%). Generalized linear mixed models and/or generalized linear models were constructed to evaluate the effect of four life history and eight social variables on the sex ratio. No consistent effects of these variables on the sex ratio were found and, interestingly, none of the variables associated with maternal life history had any effect on the sex ratio. Three factors associated with group composition (i.e. the number of immature males, the number of immature females and the number of breeding females) did have significant effects on the sex ratio, but these effects were not consistent across the studied species. In conclusion, our evaluation of this large dataset revealed that the sex ratio in spiny mice is surprisingly stable.

The Work of Breastfeeding

The Work of Breastfeeding Cindy A. Stearns (bio) Breast milk is now the gold standard for infant feeding. The encouragement to breastfeed is consistent in a range of public forums. In the United States, all the major medical and public health organizations are strong promoters of breastfeeding, citing the health benefits to both baby and mother (Kukla 2006). The American Academy of Pediatrics describes human milk as "uniquely superior for infant feeding" (2005, 1). Recommendations to breastfeed are echoed in popular baby care manuals (Knaak 2005), in a recent Department of Health and Human Services–sponsored advertising campaign (Wolf 2007), and in guidelines for supplemental government food programs for women and children (USDA 2005). In line with public health messages about the value of breast milk for babies, breastfeeding is increasingly a symbol and a measure of good mothering in the West (Avishai 2007; Lee 2007). Murphy suggests that by "deciding to formula feed, the woman exposes herself to the charge that she is a 'poor mother' who places her own needs, preferences or convenience over her baby's welfare. By contrast, the 'good mother' is deemed to be one who prioritizes her child's needs even (or perhaps especially) where this entails personal inconvenience or distress" (1999, 187–88). Breastfeeding is thus an integral component of the child-centered and demanding maternal practices inherent in the ideology of intensive mothering (Hays 1996). Lee's recent study of mothers in Great Britain provides clear evidence of this. She describes women's despair when they can't breastfeed and must turn instead to formula and concludes "how good a mother a woman is has come to be measured by whether she breastfeeds" (2007, 1088). The cultural and medical mandate to breastfeed has important implications for the work of mothering. While often unacknowledged as such, breastfeeding is time- and labor-intensive work and it is work only mothers in families can perform. For example, child care duties such as preparing bottles of infant formula, changing diapers, and doing laundry [End Page 63] are activities that can be shared by other members of a household including men and other children. In contrast, producing breast milk is an exclusively maternal body job.1 Some previous work takes note of the maternal effort involved in the doing of breastfeeding (Bartlett 2002; Blum 1999; Kelleher 2006; Shaw 2004; Stearns 1999). However, there has not been a comprehensive exploration of breastfeeding as embodied labor and the impact this may have on women and on the division of labor in families. In a social climate that prioritizes and often valorizes breastfeeding as the gold standard for infant care, the meanings and consequences of the labor of breastfeeding demand closer scrutiny. In this paper I add to our understanding of the embodied dimensions of mothering by exploring breastfeeding as body work through an analysis of in-depth interviews with breastfeeding mothers. The concept of body work refers to "work that individuals undertake on their own bodies and to the paid work performed on the bodies of others" (Gimlin 2007, 365). In recent years, feminists and social scientists have established a growing body of empirical research on both types of body work: the body work of appearance enhancement, including practices such as cosmetic surgery, exercise, and dieting; the body work involved in paid care work of the elderly and infirm; and paid beauty work and aesthetic labor performed by workers in nail and hair salons and retail work (for a review of research in this area, see Gimlin 2007; Wolkowitz 2006). This empirical focus has produced enlightening descriptions of the subjective experience of embodiment and the gendered, racialized, and classed social relations of providing paid services to others' bodies. In the following analysis, I describe both aspects of body work identified above: work on a woman's own breastfeeding body and the unpaid maternal body work of breastfeeding a baby. Furthermore, I explore the potential impact of the body work of breastfeeding on the division of labor in families. Methods This paper is based on in-depth, open-ended interviews with sixty-six women living in California. The interviews were completed in two stages: fifty-one were interviewed from 1996...

Male spotless starlings adjust feeding effort based on egg spots revealing ectoparasite load

Parents may vary their parental behaviour and investment in reproduction in response to parasite-induced changes in the fitness prospects of their offspring. Thus, parents may use the physical condition of their offspring, or any other trait related to parasite load, to adjust parental effort. The immaculate eggs of the spotless starling, Sturnus unicolor, often become densely spotted owing to the activity of the ectoparasite carnid fly Carnus hemapterus. Spot density anticipates the intensity of fly infestation suffered by nestlings and, therefore, may serve as a cue for parents to adjust reproductive investment. By cleaning spots produced by C. hemapterus on eggs of spotless starlings, we manipulated the parasite's traces revealing its presence in broods of starlings, without modifying the level of infestation, to test whether parents use these signals to adjust reproductive effort. We found support for the hypothetical negative effect of Carnus flies since nestlings raised in nests with a higher fly load had lower body mass. The experimental egg cleaning during incubation did not change the intensity of carnid fly infestation during nestling development. However, it had a significant positive influence on paternal but not maternal effort. Our experimental results support the idea that spotless starling males adjust their effort in response to their perception of the fitness prospects of their nestlings as indirectly estimated by traces of parasites on the eggshells. As far as we know, this is the first evidence of the use of parasite traces to infer risk of parasitic infestation by animal hosts.

Duration of the second stage of labor while wearing a dental support device: A pilot study

Developing a method of maximizing maternal expulsive effort should be of great value in reducing the number of cesarean sections or instrumental deliveries. Various investigations have shown that use of a dental support device (DSD) increases the isometric strength of different muscle groups. The aim of our study was to investigate the role of a DSD in second stage of pushing. Nulliparous women with an uncomplicated singleton pregnancy course were randomly assigned either to a DSD group or to a non-device group. Duration of the second stage of labor was evaluated. Rates of cesarean section or instrumental delivery indicated for failure to descend in the second stage of labor were also evaluated. Satisfaction scores for the DSD group were evaluated (range 1-5). Sixty-four subjects were enrolled in the study. Cesarean section and instrumental delivery were performed for 12 (18.8%) and 5 (7.8%) patients, respectively. There was no difference in obstetrical and neonatal demographics between the two groups. Among 64 enrolled patients, 38 (59.3%) were evaluated for the second stage of labor (n = 19 for each group). Duration of the second stage of labor in the DSD group was significantly shorter than in the non-device group: (median 19 min (interquartile interval, IQI, 9) vs 31 min (IQI, 23)), P < 0.001. One patient in the non-device group required a vacuum extraction for failure to descend. The mode of satisfaction score for the DSD group was 5 (59.3%). Wearing a dental support device may shorten the second stage of labor, and may decrease the number of failures to descend requiring operative intervention. NCT00629369.