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PO-0654 Delayed Birth Of Next Sibling In Families With A Preterm Child: Role Of Obstetric History
  1. S Turkka1,
  2. P Näsänen-Gilmore1,
  3. M Vääräsmäki2,
  4. M Gissler3,
  5. A Pouta2,
  6. E Kajantie1,
  7. P Hovi1
  1. 1Department of Chronic Disease Prevention, National Institute for Health and Welfare (THL), Helsinki, Finland
  2. 2Department of Obstetrics and Gynecology, National Institute for Health and Welfare (THL), Oulu, Finland
  3. 3Department of Support Services, National Institute for Health and Welfare (THL), Helsinki, Finland


Background Prematurity postpones the birth of a subsequent sibling. This phenomenon is strongest in mothers with long prior interbirth interval, a proxy of fertility problems.

Aim We assessed whether a history of miscarriages explains the postponed birth of next sibling after preterm birth.

Methods We obtained pregnancy and newborn data from Finnish Medical Birth Register (Jan 1, 1987 - Sep 30, 1990). Sibling data came from the National Population Register Centre.

Of the total of 230378 singleton births we excluded 1242 (0.5%) due to death before 1 yrs. GA was missing for 2922 (1.3%) and miscarriage data for 2964 (1.3%); 225650 children remained in analyses.

We utilised Cox regression for proportional hazards to analyse the effect of GA and history of miscarriages on sibling birth.

Abstract PO-0654 Table 1

Results A low GA at birth delayed subsequent sibling birth. The effect remained unchanged after introducing miscarriages in the model.

Abstract PO-0654 Table 2

Adjusted model estimating next sibling birth

*Numbers indicate completed gestational weeks. HR, Hazard Ratio (term group, females and no miscarriages as a referent).

Conclusions Prematurity postponed subsequent sibling birth. Accounting for obstetric history left this effect unchanged.

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