Sex of the first-born and risk of preterm birth in the subsequent pregnancy

Research output: Contribution to journalJournal articleResearchpeer-review

Standard

Sex of the first-born and risk of preterm birth in the subsequent pregnancy. / Mortensen, Laust H; Nielsen, Henriette Svarre; Cnattingius, Sven; Andersen, Anne-Marie Nybo.

In: Epidemiology, Vol. 22, No. 3, 2011, p. 328-32.

Research output: Contribution to journalJournal articleResearchpeer-review

Harvard

Mortensen, LH, Nielsen, HS, Cnattingius, S & Andersen, A-MN 2011, 'Sex of the first-born and risk of preterm birth in the subsequent pregnancy', Epidemiology, vol. 22, no. 3, pp. 328-32. https://doi.org/10.1097/EDE.0b013e31820e8600

APA

Mortensen, L. H., Nielsen, H. S., Cnattingius, S., & Andersen, A-M. N. (2011). Sex of the first-born and risk of preterm birth in the subsequent pregnancy. Epidemiology, 22(3), 328-32. https://doi.org/10.1097/EDE.0b013e31820e8600

Vancouver

Mortensen LH, Nielsen HS, Cnattingius S, Andersen A-MN. Sex of the first-born and risk of preterm birth in the subsequent pregnancy. Epidemiology. 2011;22(3):328-32. https://doi.org/10.1097/EDE.0b013e31820e8600

Author

Mortensen, Laust H ; Nielsen, Henriette Svarre ; Cnattingius, Sven ; Andersen, Anne-Marie Nybo. / Sex of the first-born and risk of preterm birth in the subsequent pregnancy. In: Epidemiology. 2011 ; Vol. 22, No. 3. pp. 328-32.

Bibtex

@article{34e284d002eb4cc9863a3a9a85dc4803,
title = "Sex of the first-born and risk of preterm birth in the subsequent pregnancy",
abstract = "BACKGROUND: Recent data suggest that the chance of successfully maintaining a pregnancy may be influenced by the sex of previously born children. We explored a possible relation between sex of the first-born infant and the risk of preterm birth in the second pregnancy.METHODS: Using data from the National Medical Birth Registries in Denmark 1980-2004 and Sweden 1980-2001, we selected all women whose first and second births were singleton and who had information on sex of first-born infant and gestational age for the second (Denmark, n = 393,686; Sweden, n = 603,282). Cox proportional hazards regression analysis was used to estimate the hazard ratio of preterm birth in the second pregnancy according to the sex of the first-born infant.RESULTS: Compared with women whose first baby was a girl, women with boys had an increased risk of preterm birth in a second pregnancy (hazard ratio = 1.10 [95{\%} confidence interval = 1.07-1.13]). This result was consistent in the 2 populations. The association was not confounded by maternal age, interpregnancy interval, or sex of the second infant or by maternal characteristics that do not vary from one pregnancy to the next.CONCLUSIONS: Exposure to a male fetus may increase a woman's risk of preterm delivery in the next pregnancy. While the findings have no direct public health relevance, they may suggest new pathways by which preterm birth can occur.",
keywords = "Chi-Square Distribution, Cohort Studies, Denmark, Female, Gestational Age, Humans, Infant, Newborn, Infant, Premature, Male, Parity, Predictive Value of Tests, Pregnancy, Premature Birth, Prevalence, Proportional Hazards Models, Registries, Risk Assessment, Sex Factors",
author = "Mortensen, {Laust H} and Nielsen, {Henriette Svarre} and Sven Cnattingius and Andersen, {Anne-Marie Nybo}",
year = "2011",
doi = "10.1097/EDE.0b013e31820e8600",
language = "English",
volume = "22",
pages = "328--32",
journal = "Epidemiology",
issn = "1044-3983",
publisher = "Lippincott Williams & Wilkins",
number = "3",

}

RIS

TY - JOUR

T1 - Sex of the first-born and risk of preterm birth in the subsequent pregnancy

AU - Mortensen, Laust H

AU - Nielsen, Henriette Svarre

AU - Cnattingius, Sven

AU - Andersen, Anne-Marie Nybo

PY - 2011

Y1 - 2011

N2 - BACKGROUND: Recent data suggest that the chance of successfully maintaining a pregnancy may be influenced by the sex of previously born children. We explored a possible relation between sex of the first-born infant and the risk of preterm birth in the second pregnancy.METHODS: Using data from the National Medical Birth Registries in Denmark 1980-2004 and Sweden 1980-2001, we selected all women whose first and second births were singleton and who had information on sex of first-born infant and gestational age for the second (Denmark, n = 393,686; Sweden, n = 603,282). Cox proportional hazards regression analysis was used to estimate the hazard ratio of preterm birth in the second pregnancy according to the sex of the first-born infant.RESULTS: Compared with women whose first baby was a girl, women with boys had an increased risk of preterm birth in a second pregnancy (hazard ratio = 1.10 [95% confidence interval = 1.07-1.13]). This result was consistent in the 2 populations. The association was not confounded by maternal age, interpregnancy interval, or sex of the second infant or by maternal characteristics that do not vary from one pregnancy to the next.CONCLUSIONS: Exposure to a male fetus may increase a woman's risk of preterm delivery in the next pregnancy. While the findings have no direct public health relevance, they may suggest new pathways by which preterm birth can occur.

AB - BACKGROUND: Recent data suggest that the chance of successfully maintaining a pregnancy may be influenced by the sex of previously born children. We explored a possible relation between sex of the first-born infant and the risk of preterm birth in the second pregnancy.METHODS: Using data from the National Medical Birth Registries in Denmark 1980-2004 and Sweden 1980-2001, we selected all women whose first and second births were singleton and who had information on sex of first-born infant and gestational age for the second (Denmark, n = 393,686; Sweden, n = 603,282). Cox proportional hazards regression analysis was used to estimate the hazard ratio of preterm birth in the second pregnancy according to the sex of the first-born infant.RESULTS: Compared with women whose first baby was a girl, women with boys had an increased risk of preterm birth in a second pregnancy (hazard ratio = 1.10 [95% confidence interval = 1.07-1.13]). This result was consistent in the 2 populations. The association was not confounded by maternal age, interpregnancy interval, or sex of the second infant or by maternal characteristics that do not vary from one pregnancy to the next.CONCLUSIONS: Exposure to a male fetus may increase a woman's risk of preterm delivery in the next pregnancy. While the findings have no direct public health relevance, they may suggest new pathways by which preterm birth can occur.

KW - Chi-Square Distribution

KW - Cohort Studies

KW - Denmark

KW - Female

KW - Gestational Age

KW - Humans

KW - Infant, Newborn

KW - Infant, Premature

KW - Male

KW - Parity

KW - Predictive Value of Tests

KW - Pregnancy

KW - Premature Birth

KW - Prevalence

KW - Proportional Hazards Models

KW - Registries

KW - Risk Assessment

KW - Sex Factors

U2 - 10.1097/EDE.0b013e31820e8600

DO - 10.1097/EDE.0b013e31820e8600

M3 - Journal article

C2 - 21283010

VL - 22

SP - 328

EP - 332

JO - Epidemiology

JF - Epidemiology

SN - 1044-3983

IS - 3

ER -

ID: 34164594