If the zygote has not implanted by day ten, implantation becomes increasingly unlikely in subsequent days.A chemical pregnancy is a pregnancy that was detected by testing but ends in miscarriage before or around the time of the next expected period.Chromosomal abnormalities are found in more than half of embryos miscarried in the first 13 weeks. Half of embryonic miscarriages (25% of all miscarriages) have an aneuploidy (abnormal number of chromosomes). Common chromosome abnormalities found in miscarriages include an autosomal trisomy (22–32%), monosomy X (5–20%), triploidy (6–8%), tetraploidy (2–4%), or other structural chromosomal abnormalities (2%). Genetic problems are more likely to occur with older parents; this may account for the higher rates observed in older women.Luteal phase progesterone deficiency may or may not be a contributing factor to miscarriage. Second and third trimesters
Second trimester losses may be due to maternal factors such as uterine malformation, growths in the uterus (fibroids), or cervical problems. These conditions also may contribute to premature birth. Unlike first-trimester miscarriages, second-trimester miscarriages are less likely to be caused by a genetic abnormality; chromosomal aberrations are found in a third of cases. Infection during the third trimester can cause a miscarriage. Age
The age of the pregnant woman is a significant risk factor. Miscarriage rates increase steadily with age, with more substantial increases after age 35. In those under the age of 35 the risk is about 10% while it is about 45% in those over the age of 40. Risk begins to increase around the age of 30.
Thiamine deficiency has been described for thousands of years in Asia, and became more common in the late 1800s with the increased processing of rice. Signs and symptoms
Symptoms of beriberi include weight loss, emotional disturbances, impaired sensory perception, weakness and pain in the limbs, and periods of irregular heart rate. Edema (swelling of bodily tissues) is common. It may increase the amount of lactic acid and pyruvic acid within the blood. In advanced cases, the disease may cause high-output cardiac failure and death. Symptoms may occur concurrently with those of Wernickes encephalopathy, a primarily neurological thiamine deficiency-related condition. Beriberi is divided into four categories. The first three are historical and the fourth, gastrointestinal beriberi, was recognized in 2004:

Dry beriberi especially affects the peripheral nervous system. Wet beriberi especially affects the cardiovascular system and other bodily systems. Infantile beriberi affects the babies of malnourished mothers. Gastrointestinal beriberi affects the digestive system and other bodily systems. Dry beriberi
Dry beriberi causes wasting and partial paralysis resulting from damaged peripheral nerves. It is also referred to as endemic neuritis. It is characterized by:

Difficulty with walking
Tingling or loss of sensation (numbness) in hands and feet
Loss of tendon reflexes
Loss of muscle function or paralysis of the lower legs
Mental confusion/speech difficulties
Pain
Involuntary eye movements (nystagmus)
VomitingA selective impairment of the large proprioceptive sensory fibers without motor impairment can occur and present as a prominent sensory ataxia, which is a loss of balance and coordination due to loss of the proprioceptive inputs from the periphery and loss of position sense.