Linked to stress.  

Researchers have long known that during times of stress, the brain releases several hormones — including one called corticotropin-releasing hormone (CRH). In past research, women who deliver prematurely or have low-birth-weight babies were often found to have high levels of CRH in their bloodstream, and other studies show a greater risk of miscarriage in women reporting stress. CRH is a hormone the brain secretes in reaction to physical or emotional stress, and it is also produced in the placenta and the uterus of a pregnant woman to trigger uterine contractions during delivery.

But this new research suggests that CRH and other stress hormones may also be released elsewhere in the body, where it specifically targets localized mast cells — those best known for causing allergic reactions. Mast cells are abundant in the uterus. During stress, the local release of CRH causes these mast cells to secrete substances that can cause miscarriages.
WebMD, How Stress Causes Miscarriage, 2003

Severe stress can lead to miscarriage. However this was portrayed in the Quran 1400 years before it was discovered. In the final Hour every pregnant woman will miscarry.

[Quran 22:2] When you will see it [final Hour] every nursing mother will discard her infant, and every pregnant woman will miscarry, and you will see the people drunk, even though they are not drunk. but the punishment of Allah is severe.

The final Hour will cause every pregnant woman to miscarry. Today we know why, severe stress causes miscarriage.



Slowest source of energy.

Out of all energy sources fats is the slowest to convert to energy.

Fats serve both as energy sources for the body, and as stores for energy in excess of what the body needs immediately. Each gram of fat when burned or metabolized releases about 9 food calories (37 kJ = 8.8 kcal). Fats are broken down in the healthy body to release their constituents, glycerol and fatty acids. Glycerol itself can be converted to glucose by the liver and so become a source of energy.
Wikipedia, Fats, 2019

Fats need a lot of time to convert to energy. If you sprint for a few minutes then you won’t burn any fats. However if you run a marathon then you will burn a lot of fats. So it is the endurance activities that burn fats, not the short burst ones. This was only known recently, however this was portrayed in the Quran 1400 years before it was discovered.

[Quran 22:27] And announce the pilgrimage to humanity. They will come to you on foot, and on every skinny [animal] they will come from every deep valley.  

“Damer ضامر ” means became skinny or thin. For short journeys people used to go walking however for long journeys they used to ride animals (camels, horses…). Those animals become skinny when they travel long distances and climb out of deep valleys. However short journeys on foot will not make you skinny. Today we know why short distance walking will not make you skinny because it is the endurance activities that burn fats, not the short burst ones. Traveling long distances and climbing out of deep valleys are endurance activities that burn fats.