Childbearing patterns for Swedish mothers of twins, 1961-1999

The Nordic population registers provide a unique possibility to study the demographic behavior of very small population groups and rare events. In this paper, we study the childbearing behavior of Swedish mothers of twins between 1961 and 1999, inclusive. Our most consistent finding is that mothers of twins wait noticeably longer than women with singletons before they have another child. This apart, mothers with twins at their first birth have next-birth fertility patterns very similar to women who have two singletons at their first two births. This commonality in child-bearing behavior does not extend to higher-order births. For mothers with a singleton and a pair of twins, the progression to a third birth depends very much on whether the twins came first or second. Beside these main results our fascinating material also provides a number of descriptive findings. The Swedish twinning rate has increased since the mid-1970s in response to a growing use of fertility-stimulating treatments such as in-vitro fertilization, in parallel with similar developments in many other countries. Such medical procedures are applied mainly to women beyond prime childbearing ages. Nevertheless, we find no simple age pattern in twinning rates. Even in recent years they do not just in-crease with the woman’s age. By way of contrast, at parities beyond 3 twinning rates increase with parity when we control for calendar period, time since last previous birth, and (NB) the woman’s own age.Sweden, twin studies

Patterns of twinning for Swedish women, 1961-1999

The Nordic population registers provide a unique possibility to study the demographic behavior of small population groups and rare events. In this paper, we study the childbearing behavior of Swedish mothers of twins between 1961 and 1999, inclusive. The twinning rate has increased since the mid-1970s in response to a growing use of fertility-stimulating treatments such as in-vitro fertilization. Such medical procedures are applied mainly to women beyond prime childbearing ages. Nevertheless, we find no simple age pattern in twinning rates. They do not just increase with the woman´s age. Our most consistent finding is that mothers of twins wait noticeably longer than women with singletons before they have another child. This apart, mothers with twins at their first birth have next-birth fertility patterns very similar to women who have two singletons at their first two births. This commonality in childbearing behavior does not extend to higher-order births, though. For mothers with a singleton and a pair of twins, the progression to a third birth depends very much on whether the twins came first or second. We also discover that at parities beyond 3, twinning rates increase with parity, especially at very short durations since the previous birth.vital events

Childbearing patterns for Swedish mothers of twins, 1961-1999

The Nordic population registers provide a unique possibility to study the demographic behavior of very small population groups and rare events. In this paper, we study the childbearing behavior of Swedish mothers of twins between 1961 and 1999, inclusive. Our most consistent finding is that mothers of twins wait noticeably longer than women with singletons before they have another child. This apart, mothers with twins at their first birth have next-birth fertility patterns very similar to women who have two singletons at their first two births. This commonality in child-bearing behavior does not extend to higher-order births. For mothers with a singleton and a pair of twins, the progression to a third birth depends very much on whether the twins came first or second. Beside these main results our fascinating material also provides a number of descriptive findings. The Swedish twinning rate has increased since the mid-1970s in response to a growing use of fertility-stimulating treatments such as in-vitro fertilization, in parallel with similar developments in many other countries. Such medical procedures are applied mainly to women beyond prime childbearing ages. Nevertheless, we find no simple age pattern in twinning rates. Even in recent years they do not just in-crease with the woman’s age. By way of contrast, at parities beyond 3 twinning rates increase with parity when we control for calendar period, time since last previous birth, and (NB) the woman’s own age

Patterns of twinning for Swedish women, 1961-1999

The Nordic population registers provide a unique possibility to study the demographic behavior of small population groups and rare events. In this paper, we study the childbearing behavior of Swedish mothers of twins between 1961 and 1999, inclusive. The twinning rate has increased since the mid-1970s in response to a growing use of fertility-stimulating treatments such as in-vitro fertilization. Such medical procedures are applied mainly to women beyond prime childbearing ages. Nevertheless, we find no simple age pattern in twinning rates. They do not just increase with the woman's age. Our most consistent finding is that mothers of twins wait noticeably longer than women with singletons before they have another child. This apart, mothers with twins at their first birth have next-birth fertility patterns very similar to women who have two singletons at their first two births. This commonality in childbearing behavior does not extend to higher-order births, though. For mothers with a singleton and a pair of twins, the progression to a third birth depends very much on whether the twins came first or second. We also discover that at parities beyond 3, twinning rates increase with parity, especially at very short durations since the previous birth

Patterns of twinning for Swedish women, 1961-1999

'The Nordic population registers provide a unique possibility to study the demographic behavior of small population groups and rare events. In this paper, we study the childbearing behavior of Swedish mothers of twins between 1961 and 1999, inclusive. The twinning rate has increased since the mid-1970s in response to a growing use of fertility-stimulating treatments such as in-vitro fertilization. Such medical procedures are applied mainly to women beyond prime childbearing ages. Nevertheless, we find no simple age pattern in twinning rates. They do not just increase with the woman's age. Our most consistent finding is that mothers of twins wait noticeably longer than women with singletons before they have another child. This apart, mothers with twins at their first birth have next-birth fertility patterns very similar to women who have two singletons at their first two births. This commonality in childbearing behavior does not extend to higher-order births, though. For mothers with a singleton and a pair of twins, the progression to a third birth depends very much on whether the twins came first or second. We also discover that at parities beyond 3, twinning rates increase with parity, especially at very short durations since the previous birth.' (author's abstract)Die nordischen Bevoelkerungsregister bieten eine einzigartige Moeglichkeit, das demografische Verhalten kleiner Bevoelkerungsgruppen und seltener Ereignisse naeher zu untersuchen. Im vorliegenden Arbeitspapier wird das Geburtenverhalten von schwedischen Muettern von Zwillingen im Zeitraum 1961 bis 1999 analysiert. Die Geburtenrate von Zwillingen ist allgemein seit Mitte der 70er Jahre durch eine zunehmende Anwendung von fruchtbarkeitsfoerdernden Methoden, wie die In-Vitro-Fertilisation, gestiegen. Obwohl solche medizinischen Massnahmen meist bei Frauen, die das geburtsfaehige Alter ueberschritten haben, angewandt werden, kann nach den Ergebnissen kein einfaches Altersmuster bei den Zwillingsraten festgestellt werden. Diese steigen nicht automatisch mit dem Alter der Frau an. Hingegen wird festgestellt, dass Muetter von Zwillingen im Unterschied zu Muettern von Einzelkindern deutlich laenger warten, bevor sie sich fuer die Geburt eines weiteren Kindes entscheiden. Fuer Muetter mit einem Einzelkind und einem Zwillingspaar haengt die Entscheidung fuer eine dritte Geburt wesentlich davon ab, ob die Zwillinge an erster oder an zweiter Stelle zur Welt gekommen sind. (ICIUebers)German title: Muster von Zwillings-Geburten bei schwedischen Muettern 1961-1999Available from http://www.demogr.mpg.de/papers/working/wp-2002-031.pdf / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman