NFBC-66 is a longitudinal one-year birth cohort study from an unselected population. The original purpose of the study was to describe and analyse risk factors for perinatal deaths and low birth weight. Original names of the study were "North Finland premature birth study" and "Development study of children in North Finland". The project was later named as "The mother-child cohort study of morbidity and mortality during childhood with the special purpose of preventing mental and physical handicap" and "Cohort-66 study".
Paula Rantakallio, Professor
Cases belonging to the survey were determined by the calculated term: the series
comprised all the mothers in Finland's two northernmost provinces Oulu
and Lapland with the calculated term falling between January l - December 31, 1966.
In fact, a small
percentage of the births occurred towards the end of 1965 and early in 1967. The
calculated term, as was customary at that time, was counted from the first day of the last
menstrual period. Where this date was unknown the expected term was estimated from the
date of commencement of foetal movements and progress of the pregnancy. The study covered
all live born and stillborn infants with birth weight of 600 grams or more.
| Mothers | Deliveries |
| 12055 | 12068 |
13 women delivered twice. Notice when studying mortality of the women or other than obstetric diseases the number of cases is 12055.
| Total | Live born | Still born | Boys | Girls | Singletons | Twins |
| 12231 | 12058 | 173 | 6265 | 5964 | 11905 | 326 |
According to the Finland's central Office of Statistics, births in the study area during 1966 totalled 12527, so study population comprised 96.3 per cent of all births during 1966 in that area.
Rantakallio P.: Groups at risk in low birth weight infants and perinatal mortality.
Acta Paed Scand suppl. 193:1-71, 1969.