Early reproductive loss

Expected advances in human fertility treatments and their likely translational consequences

BACKGROUND

Due to rapid research progress in reproductive biology and reproductive clinical endocrinology, many human infertility treatments are close to potential breakthroughs and translational applications. We here review current barriers, where such breakthroughs will likely come from, what they will entail, and their potential clinical applications.

MAIN TEXT

The radical nature of change will primarily benefit older women, reduce fertility treatment costs and thereby expand access to treatment. A still widely overlooked prerequisite for implantation and normal pregnancy maintenance is timely development of maternal immunological tolerance toward an implanting paternal semi-allograft, if malfunctioning associated with implantation failure and pregnancy loss, while premature termination of tolerance appears associated with premature labor, pre-eclampsia/eclampsia and gestoses of pregnancy. Common denominators between pregnancy and invasive malignancies have again been attracting attention, suggesting that, like in malignant tumors, degrees of embryo aneuploidy may affect invasiveness and ability to "disarm" the immune system's innate response against implanting embryos. Linking tolerance to implantation, we offer evidence that the so-called "implantation window" is likely immunological rather than hormonally defined.

CONCLUSIONS

Because many here outlined treatment changes will disproportionally benefit older women, they will exert a pronounced effect on society, as increasing numbers of women at grandparental ages will become mothers.

Pregnancy losses in young Australian women: findings from the Australian Longitudinal Study on Women's Health

INTRODUCTION

Little research has examined recognized pregnancy losses in a general population. Data from an Australian cohort study provide an opportunity to quantify this aspect of fecundity at a population level.

METHOD

Participants in the Australian Longitudinal Study on Women's Health who were aged 28-33 years in 2006 (n = 9,145) completed up to 4 mailed surveys over 10 years. Participants were categorized according to the recognized outcome of their pregnancies, including live birth, miscarriage/stillbirth, termination/ectopic, or no pregnancy.

RESULTS

At age 18-23, more women reported terminations (7%) than miscarriages (4%). By 28-33 years, the cumulative frequency of miscarriage (15%) was as common as termination (16%). For women aged 28-33 years who had ever been pregnant (n = 5,343), pregnancy outcomes were as follows: birth only (50%); loss only (18%); and birth and loss (32%), of which half (16%) were birth and miscarriage. A comparison between first miscarriage and first birth (no miscarriage) showed that most first miscarriages occurred in women aged 18-23 years who also reported a first birth at the same survey (15%). Half (51%) of all first births and first miscarriages in women aged 18-19 ended in miscarriage. Early childbearers (<28 years) often had miscarriages around the same time period as their first live birth, suggesting proactive family formation. Delayed childbearers (32-33 years) had more first births than first miscarriages.

CONCLUSION

Recognized pregnancy losses are an important measure of fecundity in the general population because they indicate successful conception and maintenance of pregnancy to varying reproductive endpoints.

Stepping back to gain perspective: pregnancy loss history, depression, and parenting capacity in the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B)

Previous empirical studies of pregnancy loss have predominantly focused on complex grief response and emergent problems associated with future parenting in self-selected samples of bereaved women. This article presents findings from a retrospective secondary data analysis conducted with a racially and ethnically diverse sample of currently parenting women in the United States (N = 10,688) that examined the relationships among pregnancy loss history, current maternal depressive symptoms, and mother-infant interaction with the enrolled child. Study findings underscore a racial-ethnic disparity in pregnancy loss history for African American women, whereas current maternal depressive symptoms remain fairly constant across racial-ethnic groups. Multiple loss history is associated with a slight elevation in overall symptoms of depression, but there is no relationship between pregnancy loss history and current mother-infant interaction in the study sample. An important limitation in this study is that the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) data does not allow for inferences specific to the type of loss, gestational age of fetus, time since loss, or whether the loss was spontaneous or induced. However, study findings highlight areas of incongruity between clinical and population-based research that deserve further investigation. Ultimately, the findings from this population-based research contribute to a wider perspective regarding maternal response to reproductive loss that can inform future research and targeted bereavement support.

Prevalence and correlates of pregnancy loss history in a national sample of children and families

Public health prevalence data has consistently illustrated disparities in fetal mortality prevalence on a yearly basis, yet few studies have examined the prevalence and correlates of pregnancy loss history during the reproductive life span. Using nationally representative data from the Early Childhood Longitudinal Study, Birth Cohort, approximately 25% of childbearing women in the United States were found to have experienced one or more fetal deaths prior to the current live birth. An examination of the demographic correlates of singular and multiple loss history in age-controlled models reveals that a history of multiple loss was significantly related to African-American race, lower socioeconomic status, income below poverty, and lower maternal education. Singular loss history risk was relatively consistent across social and demographic groups with some increased risk noted only for African-American women. Predictive correlates of fetal mortality varied by racial-ethnic subpopulation in multivariate analysis. Findings from this study are discussed for their contribution to existing public health knowledge and the potential for future research focused on the experience of multiple loss and demographic groups at elevated risk.

The relationship of attachment theory and perinatal loss

Perinatal loss has recently received attention in the literature that presents it as different from other types of losses. Perinatal loss, or the loss of an infant due to miscarriage, stillbirth, or neonatal death, is a significant problem that may be best understood when viewed through the framework of attachment theory. Recent advances in medical technology, including prenatal diagnostic procedures and resulting decisions have influenced issues of both perinatal attachment and loss, and have provided challenges for the clinician. This article presents a review of current theories and research on attachment and perinatal loss, and discusses how knowledge gained from this research may be integrated into clinical practice.

Mate choice and maternal selection for specific parasite resistances before; during and after fertilization

As Hamilton & Zuk pointed out, some loci may be of special importance for sexual selection because they play a crucial role in the co-evolution between parasites and hosts. In previous work I have tried to extend Hamilton & Zuk's parasite hypothesis for sexual selection, partly by including findings of immunologists and endocrinologists: in some species, handicapping signals may specifically reveal the current needs of the immune system which depends on the host's susceptibilities to different parasites. In other species, depending on the constellation of some key variables, non-handicapping signals could directly reveal the identity of resistance genes. Despite the general conflict of interests between the sexes, sexual selection may, in these cases, lead to signallers (i.e. mostly the males) focusing on improving their offspring's survival chances instead of trying to maximize their number. Males achieve this by allowing choosy females to optimize costs and benefits of each resistance. Both parts of the extended parasite hypothesis suggest that female choice for specific heritable matequalities aim to optimize the resistance genetics of the unfertilized eggs. However, intersexual selection could go further than just choosing a mate. Here, I list the possible selection levels at which the mother and/or her ova could select for specific sperm haplotypes before, during and after the formation of the zygote. For many of these possible selection levels, evidence suggests that selection after mating might favour heterozygosity or even certain specific allele combinations at loci which are involved in the parasite-host co-evolution (e.g. the major histocompatibility complex or the transferrin locus).