Studies - 2004 Cohort

Each of the 4.231 participant children in the 2004 Birth Cohort has a very important role for the development of the health researches in an international level. This group of children has been essential for the development of public actions that aim the national and international improvement of the population's health.

The data of the 2004 Birth Cohort has proved that with serious and planned measures it is possible to reverse the huge Brazilian public health problems, such as child mortality. In 1982, when the first birth cohort study started, Pelotas had a very high child mortality rate. There were 36 deaths of every 1.000 children. Since then, the researchers aimed their analyses in preventing those deaths, and they noticed that most deaths could be avoided.

In the course of 22 years, a series of actions have been implemented at the city due to the real numbers found in the researches, in order to reduce the premature births and to implement campaigns of incentive for breastfeeding. The result was the reduction of mortality rates almost by half. In 2004, there were 19,4 deaths of every 1.000 children, and three years later this number was reduced by 12,3.

These data was only known because of the collaboration of all mothers who, a little after their childbirth, accepted to answer a lot of questions to the researchers, and allowed that their newborns were tested for measuring and weight analyses.

More than the collaboration that those mothers gave to the researchers at the hospital, they also gave their addresses and, with no immediate benefit, they have received the researchers a lot of times during many years in order that the researchers could follow their children’s development. All the available time provided by the mothers and by the own participants, and all the work that the researchers had to find those more than four thousand families, are nowadays worth for the scientific knowledge that is available for the population.

Check out some data from the 2004 Birth Cohort


  • 4.231 alive neonates at Pelotas’ hospitals.

Mother's age:

  • The mothers were from 12 to 46 years old.
  • 18,9% of all mothers were less than 20 years old.
    The maternal age grew according to the family income, so that richer mothers were 4,3 years older than poorer mothers.

Babies Sex:

  • 48,1% of female neonates.
  • 51,9% of male neonates.


  • 45,2% of the mothers had a cesarean.
    Cesarean is a medical operation in which an opening is cut in a woman’s body to take out the baby when the natural childbirth is not possible or safe.


  • 64,5% of the richer women had cesarean.
    OIt was observed that the high-risk women had less medical attention and care during their pregnancy and parturition than low-risk women.

Birth weight:

  • According to the World Health Organization (WHO), the birth weight is the most important factor for the child survival. Low birth weight babies (less than 5,5 pounds at birth) have more chances of getting sick or dying than babies with an adequate birth weight. Of the 4,231 births, there were 424 low birth weight babies.


  • 97,2% of the children were breastfed.
  • 56% of the babies were breastfed at the age of 6 months.
    It is known that non-breastfed babies have 30% more chances of dying in their first year life. The World Health Organization (WHO) recommends that children are breastfed until they are, at least, 6 months old. The breastfeeding may continue until they are 2 years old.

The rate of breastfeeding increased a lot in 22 years:

  • 1982 - the babies were breastfed for about 3,1 months.
  • 1993 - othe babies were breastfed for about 4 months.
  • 2004 - the babies were breastfed for about 6,8 months.


  • 27,6% of all mothers have smoked during their pregnancy.
    Smoking mothers’ babies had a low birth weight rate bigger than non-smoking mothers’ babies. It is known that low birth weight may cause the death of newborns.


  • Of the 4.231 births, 82 babies have died in their first year of life.
    Child mortality was 4,4 times bigger among the poorer than the richer participants. It was found that the highest risk of death occurs until the children are a year old. Owing to this, attention to children’ health during this period must be reinforced by parents and doctors.

On the one hand, the rate of breastfeeding increased a lot in 22 years:

  • 1982 - the babies were breastfed for about 3,1 months.
  • 1993 - the babies were breastfed for about 4 months.
  • 2004 - the babies were breastfed for about 6,8 months.

On the other hand, child mortality decreased in 22 years:

  • 1982 - 36 of every 1.000 children died.
  • 1993 - 21,2 of every 1.000 children died.
  • 2004 - 19,4 of ever 1.000 children died.

Even with the decrease in mortality rate, the researchers keep working to decrease more the number of deaths among children. It is known that the reduction of premature births and the breastfeeding are important factors to avoid children’s death in their first year of life.

Children’s development:

Developed children were stimulated through the following means:

  • Listening to stories told by adults.
  • Having a book of stories.
  • Visiting their friends and relatives.
  • Walking in parks.
  • Watching a little of television..

Studies have proved that besides the activities listed above, playing games, role-playing games, and guessing games stimulate children’s development in their first years of life.

Update your information

If you are part of the researched 2004 Birth Cohort group, please update your information in order that we may find you for the next research stage.



if you have doubts about any research stage, please, contact us. We would be glad to help you.

Nome: Nathlia Victria

Fone: +55 (53) 3284-1300 Ramal 368

Email: coorte2004@gmail.com


Epidemiology Postgraduate Program- Centre of Epidemiological Research