<p> <b><u>Background:</u></b> Weight gained during childbearing has significant implications for maternal and child health. Both too much and too little weight gained during pregnancy can result in adverse outcomes. Recommendations for ideal gestational weight gain (GWG) have been developed by the Institute of Medicine, but achieving these standards remains a challenge. Better understanding of the wider context in which women experience pregnancy may aid in the development of novel interventions to improve trends in healthy GWG. Neighborhoods define one such dimension of women&rsquo;s wider context that is emerging as a promising factor in this area of research. However, limited work has considered long-term exposure to neighborhood environments or the role of women&rsquo;s perceptions of their neighborhood environments in relation to either inadequate or excessive GWG. </p><p> <b><u>Methods:</u></b> This dissertation explores the associations between long- and short-term exposure to neighborhood social and socioeconomic context and GWG using data from the 1979 National Longitudinal Survey of Youth. It additionally investigates associations between objective and perceived measures of neighborhood social context in relation to GWG. The first paper investigates associations between long-term, cumulative neighborhood socioeconomic deprivation and GWG. The second paper investigates associations between objectively measured and perceptions of point-in-time neighborhood social environment and GWG. Objective neighborhood social environment is measured using neighborhood socioeconomic deprivation. Perceived neighborhood social environment is assessed from women&rsquo;s self-report of problems within their neighborhood environment. The final paper in this dissertation conducts a systematic review of the literature to characterize the reporting error associated with use of self-reported, pregnancy-related weight in efforts to move the field toward developing bias correction techniques to address methodological limitations of this measure. While not directly related to understanding neighborhoods and GWG, this issue is relevant to future studies in this area that rely on self-reported weight. </p><p> <b><u>Conclusion:</u></b> The papers included in this dissertation illustrate the importance of considering both long-term and short-term measures of neighborhood social context in order to fully understand how neighborhood environments impact inadequate and excessive GWG. In particular, long-term measures of exposure to neighborhood environments should be more fully considered in order to better understand how neighborhoods can support healthy GWG. Interventions based on this improved knowledge of the environment in which women experience weight gain during pregnancy may improve GWG outcomes and health trajectories of both mother and child. Future studies in this area may also benefit from more rigorous study of variation of reporting error in self-reported pregnancy-related weight by maternal characteristics, which will aid in the development of bias correction techniques for these widely used measures.</p>

<strong>Background</strong>: The rate of maternal death from sepsis has increased in several European countries, most notably the UK, where sepsis is now the leading cause of direct maternal death. An increase in maternal mortality also implies an increase in the number of women with severe, life-threatening morbidity. Key information gaps in the understanding of severe maternal sepsis in the UK are: the incidence, main causative organisms, infection sources, and risk factors for severe maternal sepsis. <strong>Methods</strong>: Four population-based observational studies were conducted to address these evidence gaps. <strong>Results</strong>: The incidence of severe maternal morbidity from sepsis is increasing in the UK, a trend also evident in the USA. The most common sources are respiratory tract, genital tract and urinary tract infection. The predominant organisms causing infection are E. coli, group A streptococcus, and strong circumstantial evidence of Streptococcus pneumonia. Sepsis progresses very rapidly particularly with group A streptococcal infection. Approximately 20% of women with severe sepsis progress to septic shock and 2% of women die. Risk factors for severe maternal sepsis in the UK with a large effect size are: febrile illness or antibiotics in the 2 weeks prior to onset of severe sepsis (aOR=12.1, 95% CI 8.1-18.0), caesarean section after the onset of labour (aOR= 8.1, 95% CI 4.7-14.0), multiple pregnancy (aOR= 5.8, 95% CI 1.5-21.5), infection with group A streptococcus (aOR=4.8 for progression to septic shock, 95% CI 2.2-10.8), pre-labour caesarean section (aOR= 3.8, 95% CI 2.2-6.6), low socioeconomic status (aOR=2.6, 95% CI 1.03-6.7), and operative vaginal delivery (aOR=2.5, 95% CI 1.3-4.7). Risk factors are significantly cumulative. <strong>Conclusions</strong>: Infection prior to or after delivery, even if the woman appears to be well, should be a marker for close clinical monitoring. Suspicion of group A streptococcus should be regarded as an obstetric emergency and treated ahead of laboratory confirmation.

Background: Previous research suggests that vitamin D deficiency during pregnancy may be associated with suboptimal fetal growth, but direct evidence is lacking. Our objectives were 1) to develop a method for measurement of the fetal sphenoidal fontanelle area (FA) and femur volume (FV) using 3D ultrasound; 2) to create normal charts for FA and FV; and 3) to correlate FA and FV with maternal vitamin D concentration. Methods: FA measurement in 3D was evaluated in vitro and in vivo. Different segmentation methods for FV measurement were explored. A novel FV method was described which consists of three linear measurements and a volume equation; this was validated in vitro and also by comparing FV measured sonographically to the true volume assessed by computed tomography (CT), in 6 cases following pregnancy termination. A cohort of 868 uncomplicated pregnancies was selected on the basis of strict inclusion criteria; participants underwent serial ultrasound scans for FV and multilevel modeling was used for the creation of a “prescriptive” FV chart. Finally, a different cohort of 357 healthy pregnant women had serum vitamin D levels and FV ultrasound at 34 weeks gestation and dual emission x-ray absorptiometry (DEXA) of their neonates in order to investigate the prenatal determinants of fetal bone mass. Results: FA measurement was accurate in vitro, but unreliable in vivo and was therefore abandoned. A novel FV method had excellent agreement with CT and superior repeatability compared with segmentation-based methods. A normal FV chart was created and the regression equations for the median and percentile values were presented. Vitamin D demonstrated a significant correlation with FV. Conclusions: FV is a reliable sonographic marker of skeletal growth. Maternal vitamin D deficiency is associated with reduced FV. This finding has public health implications as reduced bone mass may increase the lifetime risk of osteoporosis, through fetal programming.