作者：
Fritz, MAUniv N Carolina
Sch Med Dept Obstet & Gynecol Div Reprod Endocrinol & Infertil Chapel Hill NC 27514 USA
Practitioners of reproductive medicine have come under scrutiny and criticism because of the sharp increase in multifetal gestations during the past two decades. Several factors contribute to the problem. However, the...
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Practitioners of reproductive medicine have come under scrutiny and criticism because of the sharp increase in multifetal gestations during the past two decades. Several factors contribute to the problem. However, the negative consequences of multiple pregnancy are now generally acknowledged, and active efforts toward a solution are underway.
Objective: To calculate the frequencies of very low birth weight (VLBW) neonates among twins in a large population database. Methods: The database comprised 12,567 live-born twin pairs delivered from 1993 to 1998 in I...
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Objective: To calculate the frequencies of very low birth weight (VLBW) neonates among twins in a large population database. Methods: The database comprised 12,567 live-born twin pairs delivered from 1993 to 1998 in Israel. Low birth weight (LBW) and VLBW were defined as less than 2500 ana 1500 g, respectively. We counted the number of pairs with VLBW neonates in three combinations: VLBW-VLBW, VLBW-LBW, and VLBW-over 2500 g. We compared the subsets of nulliparas and multiparas and the frequency of like- versus unlike-sex twins. Results: The frequency of at least one VLBW twin was significantly higher among nulliparas than multiparas (odds ratio [OR] 2.3;95% confidence interval [CI] 2.1, 2.6;P < .001). For pairs with VLBW-VLBW and VLBW-LBW combinations, a significantly higher frequency was found among nulliparas than multiparas (OR 2.0;95% CI 1.7, 2.8;P < .001 and OR 2.6;95% CI 2.2, 3.1;P < .001, respectively). The risk seemed to be accentuated in like-sex twins. Overall, the risk of having at least one VLBW infant was 1:5 among nulliparas and 1:12 among multiparas. The risk of having two VLBW twins among nulliparas (1:11) was double that of multiparas (1:22). Conclusion: Nulliparas are at significantly increased risk of delivering one or two VLBW twins. (Obstet Gynecol 2000;96:400-2. (C) 2000 by The American College of Obstetricians and Gynecologists.).
As contribution to a recent debate (James, 1998; Murphy et al., 1997, 1998) the proportion of twins following ovulation induction (OI) or assisted conception (AC) in 1994 in Oxfordshire and West Berkshire was estimate...
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As contribution to a recent debate (James, 1998; Murphy et al., 1997, 1998) the proportion of twins following ovulation induction (OI) or assisted conception (AC) in 1994 in Oxfordshire and West Berkshire was estimated, and by extrapolation the natural twinning rate in England and Wales was judged to have maintained a plateau phase since the 1970s. Similar figures for 1995 and 1996 from the same study, and hence a more stable local estimate, are now provided. The proportions, as before, were estimated from women's responses to a questionnaire within a case[hyphen]control study, with ascertainment from general practitioners' records or hospital case[hyphen]notes for non[hyphen]responders or for those excluded from the study originally. In 1994, 1995 and 1996 the proportion of twins following OI/AC was overall 27% (24%, 30% and 27% respectively). Restriction to the 87% locally resident made no difference. The national crude twinning rate for those years was overall 13·3 per 1000 maternities (12·8, 13·6 and 13·4 respectively).
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