Table 1 Epidemiological definitions related to stillbirths

Fetal death: The International Classification of Diseases, Revision 10 (ICD-10) defines a fetal death as "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" without specification of the duration of pregnancy.

Early fetal deaths: According to the ICD-10, an early fetal death is death to a fetus weighing at least 500 grams (or, if birth weight is unavailable, after 22 completed weeks gestation, or with a crown-heel length of 25 centimetres or more) [57].

(Birth weight is prioritised over gestational age because when ICD 10 was developed in the 1980s birth weight was believed to be more reliably reported. However globally less than half of live births are weighed and very few stillbirths are weighed, and gestational age data is more available at least based on Last Menstrual Period.)

Late fetal deaths (stillbirths): A late fetal death is defined as a fetal death weighing at least 1000 grams (or a gestational age of 28 completed weeks or a crown-heel length of 35 centimetres or more) [57]. The ICD-10 recommends this definition for the purposes of international comparison.

Stillbirths: Stillbirth is the colloquial term commonly used term for fetal death, and is the term used in this series to refer to both early and late fetal deaths.

Stillbirth rate: As the data used here is for international comparison, all stillbirth rate data refer to late fetal deaths i.e. the number of babies born dead after 28 weeks of gestation per 1,000 total births.

Early neonatal mortality rate: The number of early neonatal deaths (deaths in the first 7 days of life) per 1,000 live births.

Perinatal period: This time interval includes some portion of late pregnancy and some or all of the first month of life. It has been used to refer to at least 10 different time periods depending on the time period cut offs used. The term "perinatal" is also used to refer to some, but not all causes of neonatal death in the ICD-10 [57]. Hence the term often causes confusion [14]. In this paper, we use perinatal deaths to include stillbirths after 28 weeks gestational age and early neonatal deaths in the first 7 days of life. In general, however, we have specified the outcome (stillbirth, or neonatal) or the cause of death where the data has allowed this distinction.