Circadian rhythm is the body's internal clock that synchronizes the body's physiological
functions according to the 24-hour sleep-wake cycle. An individual establishes a circadian
rhythm 3 months after birth, which is a progressive phase that involves regulating hormones
such as cortisol and melatonin. According to previous studies, the synchronization of
circadian rhythm between mother-infant pairs have been found to be beneficial in the growth
and development of the child by regulating a 24-hour sleep-wake cycle. However, circadian
disruption may cause excessive maternal cortisol which can be transferred to the fetus
through the placenta during pregnancy and cause growth retardation. Growth faltering during
infancy is associated with increased risks of morbidity from infections and chronic diseases
in later life. Therefore, it is important to study the relationship between maternal
circadian rhythm with synchronization of infant circadian rhythm as it may be one of the
potential factors which affects the growth and development of the child.
On the other hand, infant temperament is affected by the maternal and infant circadian rhythm
and may also be a predictor to mood disorders such as depression and anxiety. A systematic
review reported that high cortisol levels during third trimester of pregnancy is associated
with higher emotional reactivity and more difficult temperament infants. Other than the
biological factors determining infant temperament, maternal psychological wellbeing during
and after pregnancy is also an important element. It has been found that elevated maternal
stress was associated with negative infant temperament, resulting in decreased sleep quality
of the infant. Negative infant temperament may be a predictor to disordered eating behaviors
and growth development. As infant temperament is an important factor in determining growth
and development, the risk factors to negative temperament should be studied.
This study aims to determine the role of prenatal and postnatal factors with the infant
circadian rhythm and its relationship with infant growth and temperament at 6 months. This
study also includes the validation of the Chrononutrition Profile Questionnaire (CPQ) among
pregnant women. Through the validation of CPQ, future research about chrononutrition
behaviors and eating misalignment can be conducted to replace food record. The design of this
study is a prospective observational cohort study. Data will be collected during 3rd
trimester of pregnancy, whereas follow-up data on birth outcomes will be collected at birth.
At 3 months after birth, data on maternal and infant circadian rhythm will be assessed, then
data on growth and development will be collected at 6 months after birth. Data collection is
elicited through a properly designed and validated questionnaire namely Chrononutrition
Profile Questionnaire (CPQ), Harvard Light Exposure Assessment (H-LEA), sun exposure habits,
Morningness-Eveningness Questionnaire (MEQ), Positive and Negative Affect Schedule (PANAS),
Pittsburgh Sleep Quality Index (PSQI), and Edinburgh Postnatal Depression Scale (EDPS).
Meanwhile, anthropometric data such as gestational weight gain and birth outcomes are
gathered from clinic record. In addition, data on infant sleep, feeding, behavior, and light
exposure will be collected using Brief Infant Sleep Questionnaire (BISQ), infant feeding log,
Baby Eating Behavior Questionnaire (BEBQ), Infant Behavior Questionnaire- Revised (IBQ-R),
and infant light exposure log sheet. Cortisol levels will be determined using salivary
cortisol method where maternal and infant saliva samples are collected at 3 time points: upon
awakening, noon (10:00 to 12:00), and evening (19:30 to 21:00). Understanding the potential
factors affecting infant circadian rhythm offers new insights in understanding modern
lifestyle factors and its association with fetal programming, infant growth, and development.