1. Perinatal Epidemiology
Andres Bolzan
Hospital Maternoinfantil, San Clemente, Argentina. Sociedad Latinoamericana de Investigación Pediátrica

2. Andrés Bolzán
Anthropologist, founder member of the Argentinian Association of Biological Anthropology responsible for perinatal epidemiologic surveillance . Hospital San Clemente, Buenos Aires, Argentina.

3. The aim of perinatology is to offers health care for persons in gestation, pregnancies and their newborns
Perinatology considers the process from 28 weeks of gestation to the first 28 days of life as a continuous line

4. The facts:

5. We may handle all the information about pregnancies and newborns with a few epidemiologic tools performed by the Latinoamerican Centre for Perinatology and Human Development

6. Tools for perinatal epidemiology surveillance
The Basic Perinatal History
The Perinatal Information System
The Perinatal Card

7. There are some basic concepts in perinatal epidemiology :

8. MEASURING PERINATAL MORTALITY
PERINATAL I
PERINATAL II

9. RATES FOR THE STUDY OF PERINATAL PROBLEMS
Global rates
Specific rates
Risk rates

10. Global Rates: e.g.: Early Neonatal Mortality = Perinatal I Mortality =
Number of newborns deaths < 7 days
Total of newborns for the period
Perinatal I Mortality =
Late fetal + Early Neonatal deaths
Total number of deliveries for the period

11. Specific Rates, e.g.:
Contribution of low birth weight to perinatal mortality
fetal + neonatal deaths < grs
Total of perinatal deaths
Fetal mortality due to eclampsia
fetal deaths whose mothers have had eclampsia
Total of fetal deaths

12. Atributable Risk in the population
Risk Rates
Odds Ratio: for case-control studies
Risk Ratio: for cohort studies
Atributable Risk in the population
(supercourse lecture )

13. Basic statistics in Perinatal Epidemiology
I. Obtaining the Basic Data

14. What are the basic data we should take into account ?
Identification of the pregnancy
obstetric history
actual pregnancy data
labour and delivery
maternal and neonatal problems
maternal and neonatal discharge

15. We can use two registration forms:
1) Perinatal Card: for the mother: is like the PBH, and has got all the basic data. Also is the reference system, because the mother keeps it during all the pregnancy and brings it everywhere for perinatal assistance.
2) Perinatal Basic History (PBH): for the health service. The basic data should be registred there.

16. Basic statistics in Perinatal Epidemiology
II. Analyzing the data

17. There are two levels of analysis :
The Basic Perinatal Statistics: for descriptive epidemiologic purposes
The analytical level: for the estimation of risk groups.

18. Basic Statistics
We may use the Basic Statistic (mortality , morbidity etc.) and the Aditional Statistics (evaluation of prenatal care, breastfeeding, maternal hospitalization etc.) programs of the Perinatal Information System . Then, we´ll be able to describe global rates and some specific rates.

19. Analytical statistics
We may use the Estimation Risk program of the Perinatal Information System and/or importing data to the Epiinfo or to the Spss programs as .dbf file . To measure the risk, the following data may be defined:

20. For the risk factor: range of exposed (lower and higher limits) range of not exposed (idem) For the result: adverse outcome (lower and higher limits) reference outcome (idem) let´s see an example:

21. Risk Factor: Body mass index during pregnancy
Exposed: mothers with BMI under - 1 standard deviation at last prenatal visit (<35 weeks of gestation). Not exposed; mother >= -1 standard deviation

22. Adverse result: Intrauterine growth retardartion: damage: weight by gestational age < 10th centile Reference outcome: newborn whose weight by gestational age is > = 10th. Centile Acta Med. Auxol, 31(1), 9-13, 1999

23. The power of data
Managment of the results for your local research

24. Once we ´ve made basic and additional statistics we are able to:
Do an epidemiologic report
Explore the real causes of morbidity and mortaltity in order to reduce it.
Have an epidemiologic baseline to make health programs.

25. The reliability of the epidemiologic indicators depends on wether the Perinatal Clinical Forms were filled in completely Then, our first step as an epidemiologist is to recomend the fill of the perinatal histories as good as possible.