Objective To compare the perinatal outcome of singleton and twin pregnancies between natural and assisted conceptions. Design Systematic review of controlled studies published [1985][1986][1987][1988][1989][1990][1991][1992][1993][1994][1995][1996][1997][1998][1999][2000][2001][2002]. Studies reviewed 25 studies were included of which 17 had matched and 8 had non-matched controls.

Two recently published meta-analyses of controlled trials of a wide variety of progestational agents, used in pregnancy (Daya 1989; Goldstein et aE. 1989), prompted this third meta-analysis of placebocontrolled trials involving the prophylactic use of a single agent, 1701hydroxyprogesterone caproate. Of seven relevant published reports of controlled trials, six had involved women considered to be at high risk of miscarriage or preterm birth. This analysis provides no support for the view that 1701-hydroxyprogesterone caproate protects against miscarriage, but suggests that it does reduce the occurrence of preterm birth. The latter effect was rcflected in a reduced rate of low birthweight babies, but not in a statistically significant reduction in perinatal mortality and morbidity. The difference between this meta-analysis and the two earlier meta-analyses illustrates the problems both of selective subgrouping and of comprehensive pooling of data from small trials.A communication by Allen et al. (1935) reported their agreement to use henceforth only the name progesterone for the pregnancy-maintaining hormone extracted from corpora lutea previously known a5 luteosteron and progestin. Their communication appearedon the same pagc that introduced 'prostaglandin' for the first time (von Euler 1935). It was not to Ibe anticipated, however, that SO years later there would be wide consensus on the effects of prost,aglandin administration, but not on the effects of progesterone administration in pregnancy.Recently, Daya (1989) and Goldstein et al. (1989) rcportcd scparatc mcta-analyses assessing the effects of prngestogen administration in pregnancy, but reached contradictory conclusions. Daya (1989) concluded that the available evi-

1976) Contribution of preterm delivery to perinatal mortality. Br Med J 2, 965. (1973) Prostaglandin F2a concentrations in peripheral blood during the first stage of normal labour. Br Med J 1,709-71 1. Tumbull A. C. (1957) Uterine contractions in normal and abnormal labour. J Obstet Gynaecol Brit Emp 64, 321. Uldbjerg N. (1989) Cervical connective tissue in relation to pregnancy, labour and treatment with prostaglandin E,. Acta Obstet Gynecol Scand Suppl148.

Aims: To assess pregnant women's opinions on and perceptions of oral health and their relationship to oral hygiene and dental care practices. Methods: Questionnaire survey on perceived oral health, oral hygiene and utilization of dental services among 649 nulliparae attending for antenatal care at all public antenatal clinics in Adelaide, South Australia. Results: Women rated their general health significantly better than their oral health (P-0.001) and attributed more importance to healthy teeth for their baby than for themselves (P-0.001). Only 35% had dental care during pregnancy; 35% had no dental visit for at least two years and 27% reported cost as a major deterrent. Eighteen percent had experienced gingival bleeding before pregnancy and 41% during pregnancy. Gingival bleeding outside pregnancy was clearly related to perceived oral health (P-0.001), but this was less so for bleeding during pregnancy. The latter was not related to age, level of education, employment, marital status, or smoking habits. Only 38% of women with gingival bleeding in pregnancy had a dental care visit in pregnancy and 28% considered their oral health as very good. Conclusions: Many pregnant women do not perceive gingival bleeding as indicating inflammatory disease and seek no professional help for it. Maternity care providers need to devote more attention to oral health in antenatal clinics and antenatal education.