Union Commitment, Parental Status, and Sibling Relationships as Sources of Stepfamily Fertility in Austria, Finland, France, and West Germany 1 Dr. Elizabeth Thomson 2 Department of Sociology and Center for Demography and Ecology University of Wisconsin-Madison, Madison, WI 53706 USA Prof. Dr. Jan M. Hoem, Dr. Andres Vikat, Dr. Alexia Prskawetz Max Planck Institute for Demographic Research Doberanerstrasse 114, 18057 Rostock, Germany Ms. Isabella Buber Institut für Demographie, Österreichische Akademie der Wissenschaften Hinter Zollamtsstrasse 2B, A-1033 Wien, Austria Dr. Laurent Toulemon Division Enquêtes et études démographiques Institut national de la statistique et des études économiques Timbre F170, 18 Bd A. Pinard - 75675 Paris Cedex 14, France Dr. Ursula Henz Swedish Institute for Social Research Stockholm University, S-106 91 Stockholm, Sweden Ms. Amy L. Godecker Department of Sociology and Center for Demography and Ecology University of Wisconsin-Madison, Madison, WI 53706 USA February 29, 2000 We investigate the differential value of first and second births in a union for couples with and without a pre-union birth. In Finland and West Germany, we find support for the value of a first union birth to signal the couple’s commitment. Birth rates are higher if the couple has no shared children, net of their total (hers, his) parity. No such effects are found in Austria or France. We find little support for the value of biological parenthood; in stepfamilies, birth rates are not higher if one partner is not a parent than when both have pre-union children. Except in Austria, we find evidence for the value of a full sibling; among couples with total parity two or more, those who have only one shared child are more likely to have another child than couples who already share two children. Prepared for the Fertility and Family Surveys Flagship Conference, May 2000 Plenary Session 4: “Partnership and Fertility Behaviors as Inter-dependent Processes”