The association of beta‐2 adrenoceptor genotype with short‐cervix mediated preterm birth: a case–control study. (20th January 2015)

• Record Type: Journal Article
• Authors: Miller, R; Smiley, R; Thom, EA; Grobman, WA; Iams, JD; Mercer, BM; Saade, G; Tita, AT; Reddy, UM; Rouse, DJ; Sorokin, Y; Blackwell, SC; Esplin, MS; Tolosa, JE; Caritis, SN; Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal‐Fetal Medicine Units (MFMU) Network
• Is Part Of: BJOG. Volume 122:Number 10(2015:Oct.)
• Page Start: 1387
• Page End: 1394
• Publication Date: 2015-01-20
• Subjects: Obstetrics -- Periodicals; Gynecology -- Periodicals; 618
• DOI: 10.1111/1471-0528.13243
• Languages: English
• ISSNs: 1470-0328

Abstract

<abstract abstract-type="main" id="bjo13243-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bjo13243-sec-0001" sec-type="section"> <title>Objective</title> <p>To determine whether <italic>β</italic><sub>2</sub>‐adrenoceptor (<italic>β</italic><sub>2</sub>AR) genotype is associated with shortening of the cervix or with preterm birth (PTB) risk among women with a short cervix in the second trimester.</p> </sec> <sec id="bjo13243-sec-0002" sec-type="section"> <title>Design</title> <p>A case–control ancillary study to a multicentre randomised controlled trial.</p> </sec> <sec id="bjo13243-sec-0003" sec-type="section"> <title>Setting</title> <p>Fourteen participating centres of the Maternal‐Fetal Medicine Units Network of the <italic>Eunice Kennedy Shriver</italic> National Institute of Child Health and Human Development.</p> </sec> <sec id="bjo13243-sec-0004" sec-type="section"> <title>Population</title> <p>Four hundred thirty‐nine women, including 315 with short cervix and 124 with normal cervical length.</p> </sec> <sec id="bjo13243-sec-0005" sec-type="section"> <title>Methods</title> <p>Nulliparous women with cervical length <30 mm upon a 16–22‐week transvaginal sonogram and controls frequency‐matched for race/ethnicity with cervical lengths ≥40 mm were studied. <italic>β</italic><sub>2</sub>AR genotype was determined at positions encoding for amino acid residues 16 and 27.</p> </sec> <sec id="bjo13243-sec-0006" sec-type="section"> <title>Main outcome measures</title> <p>Genotype distributions were compared between case and control groups. Within the short cervix group, pregnancy outcomes were compared by genotype, with a primary outcome of PTB <37 weeks.</p> </sec> <sec id="bjo13243-sec-0007" sec-type="section"> <title>Results</title> <p>Genotype data were available at position 16 for 433 women and at position 27 for 437. Using a recessive model testing for association between short cervix and genotype, and adjusted for ethnicity, there was no statistical difference between cases and controls for Arg16 homozygosity (OR 0.7, 95% CI 0.4–1.3) or Gln27 homozygosity (OR 0.9, 95% CI 0.3–2.7). Among cases, Arg16 homozygosity was not associated with protection from PTB or spontaneous PTB. Gln27 homozygosity was not associated with PTB risk, although sample size was limited.</p> </sec> <sec id="bjo13243-sec-0008" sec-type="section"> <title>Conclusions</title> <p> <italic>β</italic> <sub>2</sub>AR genotype does not seem to be associated with short cervical length or with PTB following the second‐trimester identification of a short cervix. Influences on PTB associated with <italic>β</italic><sub>2</sub>AR genotype do not appear to involve a short cervix pathway.</p> </sec> </abstract>