Introduction
Preterm Labor (PTL) is one of the most important problems of
obstetricians and the most common cause of infant mortality. A premature
labor is a labor whose pregnancy lasts less than 37 weeks
(1). In different regions, the prevalence
of PTL is about 5-10% of all pregnancy cases. Studies in different
countries show that, despite a decrease in infant mortality over the
past 20 years, PTL has a high prevalence, so that it is between 12-13%
in the United States and 5-7% in Europe
(2). The majority of preterm labors in the
world occurs in South Asia and sub-Saharan Africa
(3). In Iran, the prevalence of preterm
labor is high, and it has been reported as about 4.39 to 6.5 in various
studies (4).
PTL has different influencing risk factors
(5). Preeclampsia and/or fetal growth
restriction (FGR) are mainly medical reasons for one-third of PTLs, and
spontaneous preterm labor is two-thirds of PTLs. Prevention of PTL is
one of the most important purposes of birthing specialist care
(6). Because there are many reasons for
this problem, different types of scientific search and clinical
strategies are needed to prevent it (7).
For a desirable PTL prevention method, a combination of three items
including maternal risk factors, obstetric history, and screening tools
should be considered for stratification of risk
(5).
Contractions of the uterine during pregnancy are monitored to evaluate
PTL threat. External measurement of uterine electrical activity is known
as a substitute way of monitoring and analyzing uterine contractions.
Tocodynamometry (TOCO) is the most common tool
(8). Besides the benefits, TOCO has some
disadvantages that negatively affect correct identification of PTL
(9). So, a more accurate method is needed.
Another method is electrohysterogram (EHG), which was developed in the
1960s (10). It is a signal related to
electrical waves emitted by smooth muscle cells of the uterus, which is
also known as the uterine contraction signal
(11). EHG provides better results in
aspects of accuracy and reliability compared with tocodynamometry
(12).
Because uterine activity related to PTL often cannot be identified by
patients, home uterine activity monitoring can be suitable for early
detection of uterine contractions without hospitalization. Various
devices for this purpose were created and studies performed to evaluate
their efficacy. Some studies show that using a home uterine activity
monitoring device can increase the length of pregnancy in women with
high PTL risk (13). This leads to a
decrease in infant mortality, because gestational age has an inverse
relationship with the risk of neonatal morbidity and mortality
(14).
In Iran, the prevalence of PTL is high, and accessibility to health
facilities in some regions is low. A home monitoring device could be a
good option. Regarding this, we decided to develop a tool to monitor
uterine activity at home for pregnant women. Also, the noises of EHG
signals were removed by the composition of filters and amplifiers.