Sports fans will create noise in an attempt to distract other teams, and some sports teams have been known to create artificial noise in an attempt to make the stadium louder. In doing that, workers, teams, and fans may be at potential risk for damage to the auditory system. NIOSH conducted a health hazard evaluation and studies at Monster Trucking and Stock Car racing events, spectators average noise levels ranged from 95 to 100 dBA at the Monster Truck event and over 100 dBA at the stock car racing event. NIOSH researchers also published noise exposure levels for drivers, crew members, and staff. Noise levels at the Bristol Motor Speedway ranged from 96 dBA in the stands to 114 dBA for a driver inside a car during practice. Peak noise levels in the Pit area reached or exceeded 130 dB SPL, a level often associated with human hearing threshold for pain. Several prominent NASCAR drivers have complete or partial hearing loss and other symptoms from their many years of exposure.During the FIFA World Cup in 2010, noise levels created by fans blowing Vuvuzela averaged 131 dBA at the horn opening and 113 dBA at 2 meter distance. Peak levels reached 144 dB SPL, louder than a jet engine at takeoff.A study of occupational and recreational noise exposure at indoor hockey arenas found noise levels from 81 dBA to 97 dBA, with peak sound pressure levels ranging from 105 dB SPLto 124 dB SPL.
A blighted ovum is a pregnancy in which the embryo never develops or develops and is reabsorbed. In a normal pregnancy, an embryo would be visible on an ultrasound by six weeks after the womans last menstrual period. Anembryonic gestation is one of the causes of miscarriage of a pregnancy.A blighted ovum or anembryonic gestation is characterized by a normal-appearing gestational sac, but the absence of an embryo. It likely occurs as a result of early embryonic death with continued development of the trophoblast. When small, the sac cannot be distinguished from the early normal pregnancy, as there may be a yolk sac, though a fetal pole is not seen. For diagnosis, the sac must be of sufficient size that the absence of normal embryonic elements is established. The criteria depends on the type of ultrasound exam performed. A pregnancy is anembryonic if a transvaginal ultrasound reveals a sac with a mean gestational sac diameter (MGD) greater than 25 mm and no yolk sac, or an MGD >25 mm with no embryo. Transabdominal imaging without transvaginal scanning may be sufficient for diagnosing early pregnancy failure when
an embryo whose crown–rump length is 15 mm or more has no visible cardiac activity. See also
Ovum
Products of conception

References
External links

Blighted Ovum on WebMD
Anembryonic pregnancy on Radiopaedia.org
Johnson, MR; Riddle, AF; Sharma, V; Collins, WP; Nicolaides, KH; Grudzinskas, JG (January 1993). "Placental and ovarian hormones in anembryonic pregnancy". Human Reproduction (Oxford, England). 8 (1): 112–5. doi:10.1093/oxfordjournals.humrep.a137857. PMID 8458911.