In this article, we introduce some simple models, based on rolling dice, to explore mechanisms proposed to explain planetary habitability. The idea is to study these selection mechanisms in an analytically tractable setting, isolating their consequences from other details which can confound or obscure their effect in more realistic models. We find that the observable of interest, the face value shown on the die, \"improves\" over time in all models. For two of the more popular ideas, Selection by Survival and Sequential Selection, this is down to sampling effects. A modified version of Sequential Selection, Sequential Selection with Memory, implies a statistical tendency for systems to improve over time. We discuss the implications of this and its relationship to the ideas of the \"Inhabitance Paradox\" and the \"Gaian bottleneck.\"

BACKGROUND: Little research has been conducted on the impact of the coronavirus disease 2019 (COVID-19) pandemic on either birth outcomes or the ability of archival medical records to accurately capture these outcomes. Our study objective is thus to compare the prevalence of preterm birth, stillbirth, low birth weight (LBW), small for gestational age (SGA), congenital microcephaly, and neonatal bloodstream infection (NBSI) before and during the first wave of the COVID-19 pandemic in Kinshasa, Democratic Republic of Congo (DRC).
METHODS: We conducted a facility-based retrospective cohort study in which identified cases of birth outcomes were tabulated at initial screening and subcategorized according to level of diagnostic certainty using Global Alignment of Immunization Safety Assessment in pregnancy (GAIA) definitions. Documentation of any birth complications, delivery type, and maternal vaccination history were also evaluated. The prevalence of each birth outcome was compared in the pre-COVID-19 (i.e., July 2019 to February 2020) and intra-COVID-19 (i.e., March to August 2020) periods via two-sample z-test for equality of proportions.
RESULTS: In total, 14,300 birth records were abstracted. Adverse birth outcomes were identified among 22.0% and 14.3% of pregnancies in the pre-COVID-19 and intra-COVID-19 periods, respectively. For stillbirth, LBW, SGA, microcephaly, and NBSI, prevalence estimates were similar across study periods. However, the prevalence of preterm birth in the intra-COVID-19 period was significantly lower than that reported during the pre-COVID-19 period (8.6% vs. 11.5%, p < 0.0001). Furthermore, the level of diagnostic certainty declined slightly across all outcomes investigated from the pre-COVID-19 to the intra-COVID-19 period. Nonetheless, diagnostic certainty was especially low for certain outcomes (i.e., stillbirth and NBSI) regardless of period; still, other outcomes, such as preterm birth and LBW, had moderate to high levels of diagnostic certainty. Results were mostly consistent when the analysis was focused on the facilities designated for COVID-19 care.
CONCLUSIONS: This study succeeded in providing prevalence estimates for key adverse birth outcomes using GAIA criteria during the COVID-19 pandemic in Kinshasa, DRC. Furthermore, our study adds crucial real-world data to the literature surrounding the impact of the COVID-19 pandemic on maternal and neonatal services and outcomes in Africa.

Since the establishment of the Global Alignment of Immunization Safety Assessment in pregnancy (GAIA) case definitions in 2015, there has been an urgent need for field validation of pharmacovigilance feasibility in low- and middle-income countries. In this study, we assess the availability and quality of archival medical records at ten randomly selected high-traffic maternity wards in Kinshasa province, Democratic Republic of Congo (DRC).
A retrospective cohort of mother-child pairs was established from all recorded births taking place at study sites between July 1, 2019 to February 28, 2020 through digitization of medical records. Adverse birth outcomes and maternal vaccination status, where available and linkable, were defined according to GAIA. Basic demographic information on mothers and newborns was also tabulated; birth outcomes were assessed for both intra-site prevalence and a pooled prevalence.
A total of 7,697 mother-newborn pair records were extracted, with 37% of infants screening positive as cases of adverse outcomes. Maternal vaccination information was linkable to 67% of those cases. In total, 51% of stillbirths, 98% of preterm births, 100% of low birthweight infants, 90% of small for gestational age infants, 100% of microcephalic infants, and 0% of neonatal bloodstream infections were classifiable according to GAIA standards following initial screening. Forty percent of case mothers had some indication of tetanus vaccination prior to delivery in their medical records, but only 26% of case mothers met some level of GAIA definition for maternal vaccination during the pregnancy of interest.
Archival birth records from delivery centers can be feasibly utilized to screen for stillbirth and maternal tetanus vaccination, and to accurately classify preterm birth, low birthweight, small for gestational age, and congenital microcephaly. Assessment of other neonatal outcomes were limited by inconsistent postpartum infant follow-up and records keeping.

Ecology and evolutionary biology have focused on how organisms fit the environment. Less attention has been given to the idea that organisms can also modify their environment, and that these modifications can feed back to the organism, thus providing a key factor for their persistence and evolution. There are at least three independent lines of evidence emphasizing these biological feedback processes at different scales: niche construction (population scale); alternative biome states (community scale); and the Gaia hypothesis (planetary scale). These feedback processes make us rethink traditional concepts like niche and adaptation. We argue that organism-environment feedbacks must become a regular part of ecological thinking, especially now that the Earth is quickly changing.

The Gaia hypothesis considers the life-environment coupled system as a single entity that acts to regulate and maintain habitable conditions on Earth. In this paper we discuss three mechanisms which could potentially lead to Gaia: Selection by Survival, Sequential Selection and Entropic Hierarchy. We use the Tangled Nature Model of co-evolution as a common framework for investigating all three, using an extended version of the standard model to elaborate on Gaia as an example of an entropic hierarchy. This idea, which combines sequential selection together with a reservoir of diversity that acts as a \'memory\', implies a tendency towards growth and increasing resilience of the Gaian system over time. We then discuss how Gaian memory could be realised in practice via the microbial seed bank, climate refugia and lateral gene transfer and conclude by discussing testable implications of an entropic hierarchy for the study of Earth history and the search for life in the universe. This paper adds to the existing taxonomy of Gaia hypotheses to suggest an \"Entropic Gaia\" where we argue that increasing biomass, complexity and enhanced habitability over time is a statistically likely feature of a co-evolving system.

A globally standardized approach in high and low and middle-income countries (LMIC) to actively monitor the safety of vaccines for pregnant women during development and implementation phases is critical. Brighton Collaboration\'s (BC) Global Alignment of Immunization Safety Assessment in Pregnancy (GAIA) project has developed globally standardized case definitions (CDs) of key obstetric and neonatal terms for the assessment of safety of vaccines in pregnancy. CDs are categorized into levels of diagnostic certainty, facilitating their use in varied settings. This study evaluates the field performance of CDs in LMIC.
Data from pregnant participants of RCTs for trivalent inactivated influenza vaccine conducted at Chris Hani Baragwanath Academic Hospital, South Africa (SA) between 2011 and 2013 were reviewed retrospectively for preterm birth, stillbirth and hypertension CDs and the Gestational age assessment (GA) algorithm. Data from an ongoing pneumococcal vaccine trial (conducted at MRC Unit, The Gambia) were collected prospectively for GA.
For GA, 600 mother-infant dyads from Gambia and 155 mother-infant dyads from SA were reviewed. Level 2B (unsure LMP and US in 2nd trimester) was the most common level seen in Gambia (63%) and level 3B1 (unsure LMP with physical examination) in SA (43%). Preterm deliveries had similar results in SA. The pregnancy-induced hypertension definition performed well, with 96% (54/56) of cases fulfilling \'level 1\' for \'preeclampsia with severe features\'. 24 stillbirths were identified and 21 records were reviewed; 73.3% (11/15) of the stillbirths classified as antepartum by attending physicians and 83.3% (5/6) of the intrapartum stillbirths did not fulfil the criteria for any level of certainty.
BC CDs for neonatal and maternal outcomes (preterm and hypertension) and GA were sensitive, reliable and feasible to use in RCTs in SA and Gambia. Modifications to the stillbirth CD are required to improve its usefulness in varied settings.

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We modify the Tangled Nature Model of Christensen et. al. (2002) so that the agents affect the carrying capacity. This leads to a model of species-environment co-evolution where the system tends to have a larger carrying capacity with life than without. We discuss the model as an example of an entropic hierarchy and some implications for Gaia theory.