Inter-pregnancy intervals of less than 18 months are associated with higher risks of adverse pregnancy outcomes.
It is not known whether short intervals are associated with increased risks among older women (>40yrs) to the same extent as among younger women.
Pregnancy spacing (ie, the time interval between one pregnancy and the next) is clinically relevant because it may increase the risk for some adverse pregnancy outcomes.
Short intervals between pregnancies are more commonly associated with adverse effects than long intervals.
The degree to which individual pregnancy spacing alters adverse pregnancy outcomes is unclear, but important, since women have some control over such spacing and thus could potentially reduce adverse outcomes.
Becoming pregnant to avoid a long inter-pregnancy interval is more problematic since a desired pregnancy may be precluded by factors such as the availability of a partner, subfertility, economic or occupational issues, or illness
Short inter-pregnancy intervals appear to be associated with increased risks for adverse pregnancy outcomes for women of all ages; maternal risks at short intervals may be greater for older women, whereas foetal and infant risks may be greater for younger women.
An interval of less than 6 months between a first and second pregnancy is associated with the diagnosis of placental abruption in the second pregnancy, irrespective of hypertensive disorders. Placental dysfunction may be one mechanism by which a short IPI increases the risk of preterm birth.