Studies in modern times have observed a gradual increase in height with maternal age, though these early studies suggest that trend is due to various socio-economic situations that select certain demographics as being more likely to have a first birth early in the mothers life. These same studies show that children born to a young mother are more likely to have below-average educational and behavioural development, again suggesting an ultimate cause of resources and family status rather than a purely biological explanation.It has been observed that first-born males are shorter than later-born males. However, more recently the reverse observation was made. The study authors suggest that the cause may be socio-economic in nature. Nature versus nurture
The precise relationship between genetics and environment is complex and uncertain. Differences in human height is 60–80% heritable, according to several twin studies and has been considered polygenic since the Mendelian-biometrician debate a hundred years ago. A genome-wide association (GWA) study of more than 180,000 individuals has identified hundreds of genetic variants in at least 180 loci associated with adult human height. The number of individuals has since been expanded to 253,288 individuals and the number of genetic variants identified is 697 in 423 genetic loci. In a separate study of body proportion using sitting-height ratio, it reports that these 697 variants can be partitioned into 3 specific classes, (1) variants that primarily determine leg length, (2) variants that primarily determine spine and head length, or (3) variants that affect overall body size.
Fexofenadine, sold under the brand name Allegra among others, is an antihistamine pharmaceutical drug used in the treatment of allergy symptoms, such as hay fever and urticaria.Therapeutically, fexofenadine is a selective peripheral H1 blocker. It is classified as a second-generation antihistamine because it is less able to pass the blood–brain barrier and cause sedation, compared to first-generation antihistamines.It was patented in 1979 and came into medical use in 1996. It is on the World Health Organizations List of Essential Medicines. Fexofenadine has been manufactured in generic form since 2011. In 2019, it was the 283rd most commonly prescribed medication in the United States, with more than 1 million prescriptions. Medical uses
Fexofenadine is used for relief from physical symptoms associated with seasonal allergic rhinitis and for treatment of chronic urticaria. It does not cure, but rather prevents the aggravation of allergic rhinitis and chronic idiopathic urticaria, and reduces the severity of the symptoms associated with those conditions, providing relief from repeated sneezing, runny nose, itchy eyes or skin, and general body fatigue. In a 2018 review, fexofenadine, along with levocetirizine, desloratadine, and cetirizine, was cited to be a safe to use for individuals with inherited long QT syndrome. Efficacy
For the treatment of allergic rhinitis, fexofenadine is similarly effective to cetirizine, but is associated with less drowsiness than cetirizine.