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Artikkel

Kort protokoll for Den norske mor og barn-undersøkelsen

Version June 2002

Protocol The Norwegian Mother and Child Cohort Study

Background

A number of diseases among mothers and children cannot be prevented or treated efficiently, mainly due to the inability to understand causal mechanisms. We know, for instance, little about the causes of prematurity, congenital malformations and stillbirths. Cancer, rheumatoid arthritis, severe allergies, diabetes, autism and cerebral palsy are examples of conditions that occur in childhood and which should preferably be prevented or at least treated efficiently. For mothers, the etiological insight into diseases such as pelvic pain, postnatal depression, gestational diabetes, breast cancer and other chronic diseases is largely incomplete.

Research questions

The purpose of this study is to find causes of serious diseases for mothers and children. About 100 sub-projects with specific research questions have been suggested. These questions are mainly related to environmental factors, such as medications, nutrition, infections and work exposure. Genetic factors as well as the interplay between genes and the environment will be studied. Blood samples from as many fathers as possible will also be collected, allowing association studies between genes and diseases.

Design

This is a cohort study, which implies that a large group of pregnant women are recruited to take part in a follow-up that may last for many years after childbirth. Information about outcomes, for instance different diseases in mothers and children will be studied in an attempt to find information about potential causal factors. The cohort design allows nested case-control studies to be conducted whenever additional exposure data are collected or blood samples are analyzed.

Sample

The target population consists of all pregnant women and the fathers in Norway during a 4-5 year period. The sample size is 100,000 women. If this number has not been reached by the year 2005, the data collection might continue until the sample size is reached.

Variables

Exposure variables include genes, psychosocial factors, infections, use of medication, nutrition, life styles, occupational exposure, use of health services, substance abuse and socioeconomic factors as well as chemical and physical factors in the environment. Health variables include maternal and paternal history and health outcomes for the mother and child detected during and after pregnancy.

Data collection

About two weeks before the routine pregnancy ultrasound examination (around the17th week), the women are invited to partake in the study. They will receive an envelope containing an information folder, two questionnaires and a consent form. The questionnaires are focused on different exposures as well as health history. The women are informed of the voluntary nature of the project and the possibility to withdraw from the study at any time. Blood and urine samples from the women are taken at the same time as the ultrasound examination. More than 90 % of fathers accompany their partner to this examination, and fathers will be asked to take part in the study with a separate consent. If the father agrees, a blood sample will be taken from him, and he will fill in a short questionnaire on his own health, medication and occupational exposure.

The completed questionnaires and consent forms are sent to the Medical Birth Registry in Bergen. The pregnant women will receive a third questionnaire in the 30th week of pregnancy. Soon after birth a blood sample from the umbilical cord and a second sample from the mother will be taken.

A questionnaire on maternal and child health status will also be sent to the mother when the child is 6 months, 18 months and 6 years old. Health outcomes are also collected from hospital discharge registries as well as other health registries, such as the Medical Birth Registry, the Cancer Registry and the Diabetes Registry.

The biobank

All blood samples are sent to the Norwegian Institute of Public Health in Oslo, where a biobank is organised for the storing and processing of all samples. Extraction and processing of DNA for genetic studies are important issues.

Data analyses

The estimation of relative risk of disease is done by comparing the probability of any specified disease for mothers or children exposed to any genetic or environmental factor with the probability of diseases in the absence of these exposures. For many projects, such as those in sub-projects where the father is included, other statistical methods will be applied.

Project organisation

This project was initiated by two groups of researchers in perinatal epidemiology, at the Medical Birth Registry in Bergen and at the former National Institute of Public Health in Oslo. At present, it is anchored at the Norwegian Institute of Public Health, Division of Epidemiology, which also includes the Medical Birth Registry located in Bergen. The project is partly financed by the Ministry of Health and has been approved by the Parliament.

Economy

The planned ten-year data collection period has a budget of 130 million NOK. The project is not yet fully financed, which means that the data collection period may be extended. Presently, collaboration with international research groups and funding agencies is of high priority.

Per Magnus, Principal Investigator
Norwegian Institute of Public Health
P. O. Box 222 Skøyen, 0213 Oslo
Telephone: +47 22 04 23 98
Telefax: +47 22 04 23 51