Methodological Notes – Reproductive Outcomes Module
Updated: January 2019
Concepts and Definitions
An important measure of reproductive outcome, the survival of the fetus while still in utero and also shortly after birth, is the number and rate of perinatal deaths. International comparisons of perinatal mortality have been hampered by variable definitions across national jurisdictions.
WHO defines the perinatal period as commencing at 22 completed weeks (154 days) of gestation, and ending at 7 completed days after birth. This definition dates from ICD-10 and is recommended in its guidelines for reproductive health indicators http://whqlibdoc.who.int/publications/2006/924156315X_eng.pdf.
A perinatal death is thus a death (of a fetus or a neonate) within this perinatal period. WHO also specifies that the fetus should weigh at least 500 grams or has a crown-heel length of 25 cm or more. A neonate who dies between birth and 7 completed days (called early neonatal death) clearly had to be born alive first, and counted originally as a livebirth. An alternative definition of perinatal death includes fetal deaths of 28 weeks or more gestation (called late fetal deaths) and early neonatal deaths.
The WHO definition of a fetal death:
Death prior to the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of pregnancy; the death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles.
Fetal death is the preferred term, and should replace others such as “stillbirth”, “miscarriage” or “spontaneous abortion”. Fetal deaths do not include induced terminations of pregnancy (induced abortions).
CircHOB reports two sets of perinatal mortality rates based on the two definitions, PMR-1 and PMR-2:
Both rates are expressed as per 1000 total births. Region of residence refers to that of the mother. WHO’s “22+ weeks” definition is adhered to by the Nordic countries, Greenland and Faroe Islands. Canada and the United States report fetal deaths from 20 weeks and also from 28 weeks. Russia changed from the 28+ weeks definition to the 22+ weeks one in 2012. In general PMR-1 tend to be higher than PMR-2 due to the longer period and larger number of fetal deaths
Other commonly used indicators of reproductive outcomes include the distribution of livebirths by birthweight (low birth weight and high birth weight) and gestational age. CircHOB has discontinued monitoring these indicators due to gaps in the availability of publicly accessible data, especially for the regions.
Data Sources and Limitations
In calculating rates and proportions, the number of livebirths used in this module of CircHOB may differ from those reported in the fertility module, derived from the various national statistical agencies. In the case of the United States and Canada, these agencies are also the source of information on perinatal deaths, and hence the livebirth counts are identical. For the other jurisdictions, the medical births registry or office of the chief medical officer is used as the source of both the number of livebirths and the number of perinatal deaths. The livebirth counts from these sources differ from those of their national statistical agencies in that the birth registries tend to record and report only on births occurring within the country, whereas the national statistical agencies record and report on births to mothers who are citizens/permanent residents regardless of the place of delivery. Because of incomplete data capture from health care institutions, the livebirth counts in the medical births registry also tend to be lower than the counts reported by the national statistical agencies.
