Prevalence in post-menopausal women approaches that of men in the same age range. Women are at greater risk for developing OSA during pregnancy. Medication and lifestyle
Lifestyle factors such as smoking may also increase the chances of developing OSA as the chemical irritants in smoke tend to inflame the soft tissue of the upper airway and promote fluid retention, both of which can result in narrowing of the upper airway. Cigarettes may also have an impact due to a decline of blood nicotine levels, which alters sleep stability. Smokers thus show a higher risk to develop OSA, but the effect of cigarettes on increased OSA is reversible with the cessation of smoking. Children exposed to cigarette smoke may also develop OSA as the lymphadenoid tissue will proliferate excessively in contact with the irritants. An individual may also experience or exacerbate OSA with the consumption of alcohol, sedatives, or any other medication that increases sleepiness as most of these drugs are also muscle relaxants. Allergic rhinitis and asthma have also been shown to be implicated in the increased prevalence of adenotonsillar hypertrophy and OSA. Genetic
OSA also appears to have a genetic component; those with a family history of it are more likely to develop it themselves. Craniofacial syndromes
Of substantial recent interest is the idea that there is a general human tendency towards developing short lower jaws (neoteny) is a major cause of OSA through a combined condition called glossoptosis. The posterior “normal” tongue is displaced backwards by a smaller “abnormal” anterior tongue and lower jaw.
Blood findings
The blood film can point towards vitamin deficiency:

Decreased red blood cell (RBC) count and hemoglobin levels
Increased mean corpuscular volume (MCV, >100 fL) and mean corpuscular hemoglobin (MCH)
Normal mean corpuscular hemoglobin concentration (MCHC, 32–36 g/dL)
Decreased reticulocyte count due to destruction of fragile and abnormal megaloblastic erythroid precursor. The platelet count may be reduced. Neutrophil granulocytes may show multisegmented nuclei ("senile neutrophil"). This is thought to be due to decreased production and a compensatory prolonged lifespan for circulating neutrophils, which increase numbers of nuclear segments with age. Anisocytosis (increased variation in RBC size) and poikilocytosis (abnormally shaped RBCs). Macrocytes (larger than normal RBCs) are present. Ovalocytes (oval-shaped RBCs) are present. Howell-Jolly bodies (chromosomal remnant) also present.Blood chemistries will also show:

An increased lactic acid dehydrogenase (LDH) level. The isozyme is LDH-2 which is typical of the serum and hematopoietic cells. Increased homocysteine and methylmalonic acid in Vitamin B12 deficiency
Increased homocysteine in folate deficiencyNormal levels of both methylmalonic acid and total homocysteine rule out clinically significant cobalamin deficiency with virtual certainty.Bone marrow (not normally checked in a patient suspected of megaloblastic anemia) shows megaloblastic hyperplasia. See also
List of circulatory system conditions
List of hematologic conditions

References
External links

GeneReview/NCBI/NIH/UW entry on Thiamine-Responsive Megaloblastic Anemia Syndrome
Rare Anemias Foundation