The prevalence of stillbirths: a systematic review

BACKGROUND: Stillbirth rate is an important indicator of access to and quality of antenatal and delivery care. Obtaining overall estimates across various regions of the world is not straightforward due to variation in definitions, data collection methods and reporting. METHODS: We conducted a systematic review of a range of pregnancy-related conditions including stillbirths and performed meta-analysis of the subset of studies reporting stillbirth rates. We examined variation across rates and used meta-regression techniques to explain observed variation. RESULTS: We identified 389 articles on stillbirth prevalence among the 2580 included in the systematic review. We included 70 providing 80 data sets from 50 countries in the meta-analysis. Pooled prevalence rates show variation across various subgroup categories. Rates per 100 births are higher in studies conducted in less developed country settings as compared to more developed (1.17 versus 0.50), of inadequate quality as compared to adequate (1.12 versus 0.66), using sub-national sample as compared to national (1.38 versus 0.68), reporting all stillbirths as compared to late stillbirths (0.95 versus 0.63), published in non-English as compared to English (0.91 versus 0.59) and as journal articles as compared to non-journal (1.37 versus 0.67). The results of the meta-regression show the significance of two predictor variables – development status of the setting and study quality – on stillbirth prevalence. CONCLUSION: Stillbirth prevalence at the community level is typically less than 1% in more developed parts of the world and could exceed 3% in less developed regions. Regular reviews of stillbirth rates in appropriately designed and reported studies are useful in monitoring the adequacy of care. Systematic reviews of prevalence studies are helpful in explaining sources of variation across rates. Exploring these methodological issues will lead to improved standards for assessing the burden of reproductive ill-health

Data Report: Petrography and Geochemistry of Jasperoids from Site 1189, Ocean Drilling Program Leg 193

Bright red "jasperoids" were recovered at three positions during Leg 193 drilling below Roman Ruins (Site 1189) in the PACMANUS hydrothermal field. These do not represent fossil exhalative oxide deposits equivalent to those associated with sulfide chimneys at the Roman Ruins seafloor. Rather, they constitute an integral, relatively early stage involving oxidized fluids in the development of veins and breccias that characterize the mostly sulfidic stockwork zone intersected below Roman Ruins in Hole 1189B. They formed by growth of quartz in open spaces created by hydrofracturing, the characteristic feature being mostly euhedral cores dusted by tiny hematite flakes. In one occurrence there are also frondlike aggregates and possible earlier cavity linings of hematite, overgrown by quartz, that potentially formed by maturation of ferruginous gels first deposited in the openings. The trace element geochemistry of the jasperoids, apart from minor enrichment in uranium, provides no indication that they represent subsurface conduits for fluids that deposit Fe-Mn-Si at the seafloor, though this remains a possibility for some such deposits

Bikpela: A large siliceous chimney from the PACMANUS hydrothermal field, Manus basin, Papua New Guinea

The 2.7 m Bikpela chimney differs from sulfide-rich chimneys at PACMANUS, eastern Manus basin, by virtue of high silica content, a stromatolite-like layered structure, and the presence of a large internal collapse cavity. Its interior is dominated by 5-to 10-mm-thick primary laminae of opal-A-dominated fronds clouded by submicroscopic sphalerite inclusions, set between thin subhorizontal growth borders. Larger sphalerites with sulfosalt-galena intergrowths at frond ends project into discoid cavities under the growth borders. A steeper, second-order lamination reflects arrested expansion of the 50-cm-high internal collapse cavity. Underlying the cavity floor an axial breccia pipe contains distorted fragments of laminated interior modified by dissolution and then redeposition of opal and further growth of pyrite and sphalerite. Beneath a thin Mn oxide crust, a hard outer sphalerite-barite carapace ∼5 cm thick and devoid of opal is banded parallel to the chimney exterior.At least three stages of chimney growth are evident, beginning with repetitive deposition of opaline frond layers probably developed from microbial mat precursors by overgrowth of hydrothermal opal and fine sphalerite. Next, with rising fluid temperatures, hydrothermal Fe-poor sphalerite with Pb sulfosalts and galena deposited at frond ends and under growth borders and, via lateral diffusion and mixing with seawater, formed abundantly in the outer carapace of the chimney. Passage of hot, more acid fluids into the chimney axial zone then caused dissolution of primary opal and consequent formation of the collapse cavity and underlying breccia pipe, together with deposition of Fe-rich sphalerite and pyrite in second-order fractures and cavities related to the collapse. Finally, conductive cooling during or after this latter stage produced films and spherules of clear opal coating pores and grain margins throughout the structure, apart from in the carapace.Bikpela contains significant gold and silver (avg: 8.7 ppm Au, 250 ppm Ag; n = 9), but it is low overall in Cu (up to 0.5 wt % in the pipe) and Pb (up to 0.7 wt % in the carapace). Its carapace is relatively rich in Zn (up to 54 wt %), Ag, As, and Sb, with one sample containing 0.12 wt % silver

Data Report: Geochemistry of Massive and Semimassive Sulfides from Site 1189, Ocean Drilling Program Leg 193

Chemical and isotopic data for rare massive and semimassive sulfide samples cored at Site 1189 (Roman Ruins, PACMANUS) suggest their genetic relationship with sulfide chimneys at the seafloor. Sand collected from the hammer drill after commencement of Hole 1189B indicates that at least the lower section of the cased interval was occupied by material similar to the stockwork zone cored from 31 to ~100 meters below seafloor (mbsf) in this hole, but with increased content of barite, sphalerite, and lead-bearing minerals. Fractional crystallization of ascending hydrothermal fluid involving early precipitation of pyrite may explain vertical mineralogical and chemical zoning within the stockwork conduit and the high base and precious metal contents of Roman Ruins chimneys. A mineralized volcaniclastic unit cored deep in Hole 1189A possibly represents the lateral fringe of the conduit system. Lead isotope ratios in the sulfides differ slightly but significantly from those of fresh lavas from Pual Ridge, implying that at least some of the Pb within the Roman Ruins hydrothermal system derived from a deeper, more radiogenic source than the enclosing altered volcanic rocks

Description, geochemistry, mineralogy and isotopes of sulfides from ODP Site 193-1189, PACMANUS field

Chemical and isotopic data for rare massive and semimassive sulfide samples cored at Site 1189 (Roman Ruins, PACMANUS) suggest their genetic relationship with sulfide chimneys at the seafloor. Sand collected from the hammer drill after commencement of Hole 1189B indicates that at least the lower section of the cased interval was occupied by material similar to the stockwork zone cored from 31 to ~100 meters below seafloor (mbsf) in this hole, but with increased content of barite, sphalerite, and lead-bearing minerals. Fractional crystallization of ascending hydrothermal fluid involving early precipitation of pyrite may explain vertical mineralogical and chemical zoning within the stockwork conduit and the high base and precious metal contents of Roman Ruins chimneys. A mineralized volcaniclastic unit cored deep in Hole 1189A possibly represents the lateral fringe of the conduit system. Lead isotope ratios in the sulfides differ slightly but significantly from those of fresh lavas from Pual Ridge, implying that at least some of the Pb within the Roman Ruins hydrothermal system derived from a deeper, more radiogenic source than the enclosing altered volcanic rocks