Background: Circadian rhythm plays an important role as our internal body’s clock that synchronizes behavior and physiology according to the external 24-h light-dark cycle. Past studies have associated disrupted circadian rhythm with higher risk of miscarriages, preterm birth and low birth weights. This paper described the protocol of a prospective cohort study which aims to determine the circadian rhythm in pregnant women, identify its association with maternal factors during pregnancy, gestational weight gain, birth and infant outcomes. Methods: Ten government maternal and child health clinics in Kuala Lumpur, Malaysia will be randomly selected. Sample size of 438 first-trimester pregnant women will be followed-up until the birth of their infant. Salivary melatonin and cortisol concentration among subsample will be determined using enzyme-linked immunosorbent assay. Data on sleep quality, psychological distress and morningness/eveningness chronotype of pregnant women will be collected using validated questionnaires. Pedometer will be used to measure 5-day physical activity data. Total gestational weight gain will be determined at the end of pregnancy. Utilization of 3-day food record is to capture meal timing and nutrient intake. All measurements will be done in 2nd and 3rd trimester. Birth outcomes will be collected through clinic records and Centers for Disease Control and Prevention (CDC) Neonatal questionnaire. Infants will be followed-up at 6 and 12 months old to obtain anthropometric measurements. Discussion: There is a growing recognition of the role of maternal circadian rhythm, which entrains fetal circadian rhythms that may subsequently have long-term health consequences. The present study will identify the effect of circadian rhythm on pregnancy outcomes and infant growth in the first year of life.

Background: Women’s diet and nutritional status during pregnancy are important in influencing birth outcomes. We conducted a systematic scoping review of the best available evidence regarding dietary intake of Malaysian pregnant women, and the associations of maternal diet, anthropometry, and nutrition-related co-morbidities with the infant’s birth weight (IBW). The study objectives were to examine: (1) the adequacy of micronutrient intake among pregnant women; and (2) the association of maternal factors (anthropometry, diet, plasma glucose and blood pressure) during pregnancy with IBW. Methods: Eleven search engines such as Proquest, EbscoHost, Scopus, Cochrane Library, Science Direct, Wiley Online Library, PubMed, Google Scholar, MyJournal, BookSC and Inter Library Loan with Medical Library Group were extensively searched to identify the primary articles. Three reviewers independently screened the abstracts and full articles based on the inclusion and exclusion criteria. Extracted data included details about the population characteristics, study methods and key findings related to the review objectives. Seventeen studies published from 1972 to 2021 were included, following the PRISMA-ScR guideline. Results: Studies showed that maternal micronutrient intakes including calcium, iron, vitamin D, folic acid, and niacin fell short of the national recommendations. Increased maternal fruit intake was also associated with increased birth weight. Factors associated with fetal macrosomia included high pre-pregnancy body mass index (BMI), excess gestational weight gain (GWG) and high blood glucose levels. Low pre-pregnancy BMI, inadequate GWG, intake of confectioneries and condiments, and high blood pressure were associated with low birth weight. Conclusion: This review identified several factors such as the mother’s food habits, comorbidities, BMI and gestational weight gain as the determinants of low birth weight. This implies that emphasis should be given on maternal health and nutrition for the birth outcome.

Chrononutrition emerges as a novel approach to promote circadian alignment and metabolic health by means of time-of-the-day dietary intake. However, the relationship between maternal circadian rhythm and temporal dietary intake during pregnancy remains understudied. This study aimed to determine the change in melatonin levels in pregnant women across gestation and its association with temporal energy and macronutrient intake. This was a prospective cohort involving 70 healthy primigravidas. During the second and third trimesters, pregnant women provided salivary samples collected at 9:00, 15:00, 21:00, and 3:00 h over a 24 h day for melatonin assay. Data on chrononutrition characteristics were collected using a 3-day food record. Parameters derived from melatonin measurements including mean, amplitude, maximal level, area under the curve with respect to increase (AUC_I), and area under the curve with respect to ground (AUC_G) were computed. A rhythmic melatonin secretion over the day that remained stable across trimesters was observed among the pregnant women. There was no significant elevation in salivary melatonin levels as pregnancy advanced. In the second trimester, higher energy intake during 12:00–15:59 h and 19:00–06:59 h predicted a steeper melatonin AUC_I (β=-0.32, p = 0.034) and higher AUC_G (β = 0.26, p = 0.042), respectively. Macronutrient intake within 12:00–15:59 h was negatively associated with mean melatonin (Fat: β=-0.28, p = 0.041) and AUC_G (Carbohydrate: β=-0.37, p = 0.003; Protein: β=-0.27, p = 0.036; Fat: β=-0.32, p = 0.014). As pregnant women progressed from the second to the third trimester, a flatter AUC_I was associated with a reduced carbohydrate intake during 12:00–15:59 h (β=-0.40, p = 0.026). No significant association was detected during the third trimester. Our findings show that higher energy and macronutrient intakes particularly during 12:00–15:59 h and 19:00–06:59 h are associated with the disparities in maternal melatonin levels. Findings suggest the potential of time-based dietary approaches to entrain circadian rhythm in pregnant women.