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i n f orm ation on t he ea rly puerpe r a l health situation o f both
urba n and rur al mothers i n spite of thi s limitation .
I I. The pro sp ec t i v e n a t u r e of the study, exposed it to the
maj or ha za r d encountered i n this type of study. the p r o ble m o f
"SUb j e ct drop out" . This factor i ntroduc es a second selection
bias into the ou tcome s o f ch Lc strud y , A satisfactory overal l
fol l ow-up r a t e of 81.1% was cbtieLnod 101 the study even thou g h
one d i d no t en t irely escape thi s type of limi t a t i on .
Baseline characteristi cs of t he approximately 20% o f
SUbjects l ost to follow-up, we rrt available. They were f ound to
be very similar to t hose who came s pontaneously to t he clinic
an d t o those who did not at tend but were l ater f ound. It wa s ,
t h e r efore , r eass uring evi denc e t hat those who we r e not found
may n ot differ marke d ly f r om t hose seen. The selection b i a s
t hus In t.roduced by t h e loss of SUbjects during fo llow-up can
be cons idered t o be s mall.
III . About J6%: of the SUbjects seen at fo l low-up a t had
fa iled to attend ":he morbidit y assessment clinic as requested .
They wer e t r a c ed t o their homes and assessed t here. This horne
follow-up proces s was o ften achieved a f ew da y s l a t e r in t he
postpartum p e rio d a nd there f ore intr oduced time biases into
t he find i n g s r ecorded f o r thes e gro up o f women in the study
s ample.