Is there a combined dose-response effect of cigarette smoking and alcohol use during pregnancy on birth weight in a diverse western cape community of South Africa?

Nolan, Heidi (2022-04)

Thesis (MSc)--Stellenbosch University, 2022.

Thesis

Introduction: Prenatal cigarette exposure (PCE) and prenatal alcohol exposure (PAE) are associated with obstetric complications such as intrauterine growth restriction. This could lead to small for gestational age (SGA) fetuses (who are either constitutionally or pathologically small), potentially resulting in low birth weight (LBW), preterm delivery, perinatal mortality, and infant mortality. Despite public health warnings and awareness campaigns, a high prevalence of PCE (47 %) and PAE (34 – 51 %) is st ill reported in South Africa ( SA), an upper-middle-income country. This may contribute to the high prevalence (14.2 %) of preterm birth and LBW found in SA, making PCE and PAE two of the largest preventable causes of fetal/infant morbidity and mortality. Many studies have assessed the effect of PCE and PAE separately, focusing on adverse pregnancy outcomes. However, the combined dose-response relationship between PCE and PAE on birth weight remains unclear. This study aimed to determine whether there is a combined dose-response effect of cigarette smoking and alcohol during pregnancy on birth weight in a diverse cohort of a well- defined geographical area of low socioeconomic status in the Western Cape community of SA. Method: Data from the Safe Passage Study, a large, prospective, multidisciplinary study who enlisted 11 892 pregnant women of diverse ancestry residing in well-defined residential areas between August 2007 and January 2015 from two clinical sites were used. Exposure data was collected at 30-day intervals preceding the last recorded exposure. PCE was captured by asking about the participant’s smoking habits (i.e. quantity and frequency of smoking a tobacco cigarette on a typical day or chewing tobacco during a typical week) using grouped frequency options (detailed under methodology). PAE was captured using quantity questions such as sharing of drinks, duration for each drinking occasion, type/brand of beverages consumed, number, container size, and iced or frozen. All drinking was converted to number of standard drinks per day. Brink et al. formulated a nine-level alcohol- smoking exposure grouping to examine the prenatal dose-relationship on birth weight. Data from the South African cohort was used for this study. Only patients with singleton pregnancies that resulted in a live birth with birth weight, infant s ex, and gestational age (GA) recorded at birth were included. Birth weight data were converted to birth weight z- scores and centiles according to the reference ranges of the Intergrowth-21st Project and Gardosi. Distributions of z-scores and proportions of SGA (< p10, < p5 and < p3) fetuses were compared across the nine-level alcohol-smoking exposure groups, as well as the collapsed four-level alcohol-smoking exposure groups. Results: The percentage of newborns identified in our study as SGA was significantly higher than expected. Compared against the nine-level alcohol-smoking exposure grouping, the highest percentage was seen in the dual exposure groups (either or both heavy exposure). The same was seen in the smoking and drinking (SD) category when compared against the four-level alcohol-smoking exposure grouping. Conclusion: Alcohol and smoking exposure has a combined dose-response effect on birth weight and the proportion of SGA infants, especially when one or both exposures are high.

Inleiding: Prenatale sigaretblootstelling (PSB) en prenatale alkoholblootstelling (PAB) word geassosieer met verloskunde komplikasies soos intrauterine groeibeperking. Dit kan lei tot klein vir gestasie (KVG) fetusse (wat normaal of patologies klein is), wat moontlik lei tot lae geboortegewig (LGG), premature kraam, perinatale mortaliteit en babasterftes. Ten spyte van Openbare Gesondheid-waarskuwings en bewusmakingsveldtogte, word ‘n hoë voorkoms vir PSB (47 %) en PAB (34 – 51 %) steeds in Suid-Afrika (SA), ‘n hoër-middel- inkomste land, aangemeld. Dit kan bydra tot die verhoogde voorkoms (14.2 %) van premature kraam en LGG wat in SA gevind word, wat PSB en PAB twee van die grootste voorkombare oorsake van fetale/baba-morbiditeit en -mortaliteit maak. Baie studies het die effek van PSB en PAB afsonderlik nagevors met die fokus op nadelige swangerskapuitkomste. Die gekombineerde dosis-respons-verwantskap tussen PSB en PAB op geboortegewig is egter nog onduidelik. Hierdie studie se doel was om vas te stel of daar 'n gekombineerde dosis-respons-effek van sigaretrook en alkohol gebruik tydens swangerskap op geboortegewig is in 'n diverse kohort van 'n goed gedefinieerde geografiese gebied met lae sosio-ekonomiese status in die Wes- Kaapse gemeenskap van SA. Metode: Data is gebruik van die Safe Passage-studie, 'n groot, voornemende, multidissiplinêre studie wat 11 892 swanger vroue v an uiteenlopende afkoms in goed gedefinieerde woongebiede tussen Augustus 2007 en Januarie 2015 vanaf twee kliniese terreine betrek het. Blootstellingsdata was ingesamel met intervalle van 30 dae voor die laaste aangetekende blootstelling. PSB was vasgelê deur te vra oor die deelnemer se rookgewoontes deur gebruik te maak van gegroepeerde frekwensie-opsies (g edetailleerd onder metodologie) (d.w.s. hoeveelheid en gereeldheid van ‘n tabak sigaret rook op ‘n tipiese dag of tabak kou gedurende ‘n tipiese week). PAB was bepaal deur vrae soos die deel van drankies, duur van elke drinkgeleentheid, tipe/handelsmerk van verbruikte drank, aantal, houergrootte en ys of bevrore hoeveelheid. Alle gebruik van alkohol is omgesit na aantal standaard drankies per dag. Brink et al. het 'n nege-vlak alkohol-rookblootstelling groepering geformuleer om die prenatale dosis-verhouding op geboortegewig te ondersoek. Data van die Suid-Afrikaanse-kohort is vir hierdie studie gebruik. Slegs pasiënte met enkel- swangerskappe wat gelei het tot 'n lewende geboorte met geboortegewig, geslag van baba en swangerskapsduurte wat by geboorte aangeteken is, is ingesluit. Geboortegewigdata is omgeskakel na geboortegewig z-tellings en sentiele volgens die pasgebore populasie- gebaseerde verwysingsreekse van die Intergrowth-21st Projek en dié van Gardosi (aangepas by individuele pasiëntkenmerke). Verspreidings van z-tellings en proporsies van KVD (< p10) fetusse en ernstige KVD (< p5 of p3) is vergelyk oor die nege-vlak alkohol- rookblootstelling groepe sowel as die ineengestorte vier-vlak alkohol-rookblootstelling groepe. Uitslae: Die persentasie pasgeborenes wat geïdentifiseer is as KVG, is aansienlik hoër as wat volgens literatuur verwag word. In vergelyking met die nege-vlak alkohol- rookblootstelling groepering, is die hoogste persentasie hiervan gesien in die dubbele blootstelling groepe (een of albei hoë blootstelling). Dieselfde is gesien in die rook en drink (SD) kategorie wa nneer dit vergelyk word met die vier-vlak al kohol-rookblootstelling groepering. Gevolgtrekking: Alkohol en rookblootstelling het 'n gekombineerde dosis-respons-effek op geboortegewig en die proporsie van KVD-babas het, veral wanneer een of albei blootstellings hoog is.

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