Maternal plasma vitamin D status may influence circadian behaviour at mid-pregnancy
Maternal plasma 25-hydroxyvitamin D (25OHD) deficiency was associated with poor sleep quality and predominantly nighttime (pNT) feeding, particularly during the late second trimester of pregnancy, according to a recent Singapore study.
“These [findings] are of concern because 25OHD deficiency, sleep disorders, and [nighttime] eating have been linked with pregnancy complications including impaired glucose tolerance, gestational diabetes mellitus, and preeclampsia, which can in turn impair both mothers’ and offsprings’ long-term health,” said the researchers.
Researchers gathered data from the GUSTO* trial and analysed women with singleton pregnancy at 26–28 weeks’ gestation (n=890). Participants were categorized according to plasma 25OHD status (sufficient [>75 nmol/L, n=527], insufficient [50–75 nmol/L, n=244] or deficient [<50 nmol/L, n=119]). [Nutrients 2017;doi:10.3390/nu9040340]
Compared with pregnant women with sufficient plasma 25OHD, pregnant women with 25OHD deficiency had greater odds of poor sleep quality (odds ratio [OR], 3.19, 95 percent confidence interval [CI], 1.89–5.39; p<0.001) and pNT eating (OR, 1.85, 95 percent CI, 1.10–3.13; p=0.021), as well as significantly higher odds of both poor sleep quality and pNT eating (OR, 6.01, 95 percent CI, 2.55–14.16; p<0.001).
Pregnant women with insufficient 25OHD were also associated with poor sleep quality (OR, 1.47, 95 percent CI, 1.00–2.15; p=0.048).
After adjusting for biological, behavioural, and social variables, the odds remained significantly higher in all parameters for pregnant women with deficient plasma 25OHD (OR, 4.14, 95 percent CI, 2.01–8.51; p<0.001 for poor sleep quality, OR, 1.89, 95 percent CI, 0.99–3.64; p=0.055 for pNT eating, and OR, 9.74, 95 percent CI, 2.57–36.90; p=0.001 for both poor sleep quality and pNT eating).
“Notably, these women were associated with higher odds for dual circadian [behavioural] disruption, suggesting that both sleep quality and feeding patterns should be considered when assessing circadian [behaviour],” said the researchers.
The decreased endogenous vitamin D synthesis could be due to disrupted circadian rhythms, said the researchers, as this impairs gastrointestinal vitamin D absorption and kidney and liver functions involved in vitamin D production. Decreased exposure to ultraviolet radiation could also be another factor influencing plasma 25OHD levels, as pregnant women have a tendency to stay indoors, they added.
Previous studies cited geographic latitude as influential in 25OHD concentrations and sleep qualities. [Am J Epidemiol 2011;174;1363-1372; Acta Derm Venereol 2011:91;115-124; J Sleep Res 2012:21;176-184] “[However], our findings … were unlikely to be affected by seasonal changes, since the duration of day length, and sunrise and sunset times, are relatively constant all year round in Singapore,” said the researchers.
To establish the role of vitamin D in behavioural circadian rhythms during pregnancy, further trials are warranted to evaluate for reverse causality to determine whether increasing plasma 25OHD levels can improve human circadian behaviour or if improving circadian behaviour can increase plasma 25OHD levels, noted the researchers.
These findings could also be essential for creating interventional strategies that can help in preventing pregnancy complications and reducing future health concerns, they added.