]> 2026-07-31T09:41:06+00:00 WBR0081 0 en Preconception If infection occurs within 0–28 days before conception, there is a 43% chance the infant will be affected. This is not the period during which the patient is at highest risk. First trimester If the infection occurs within 0–12 weeks after conception, there is a 51% chance the infant will be affected. The first trimester is the time period during which the patient is at highest risk of transmitting rubella to her infant. Second trimester If the infection occurs within 13–26 weeks after conception there is a 23% chance the infant will be affected by the disease. This is not the trimester during which the patient is at highest risk. Third trimester Infants are not generally affected if rubella is contracted during the third trimester, or 26–40 weeks after conception. Congenital rubella syndrome results from the infection of fetus by the transmission of the virus from the mother during the viremic stage of the infection. The rubella virus travels through the blood stream of the fetus and damages the blood vessels. This results in ischemic injury to the cells in the germ layers. The risk of congenital infection and defects is highest during the first 12 weeks of gestation, and decreases after the 12th week of gestation with defects rare after the 20th week of gestation. If infection occurs within 0–28 days before conception, there is a 43% chance the infant will be affected. If the infection occurs within 0–12 weeks after conception, there is a 51% chance the infant will be affected. If the infection occurs within 13–26 weeks after conception there is a 23% chance the infant will be affected by the disease. Infants are not generally affected if rubella is contracted during the third trimester, or 26–40 weeks after conception.<br/> '''Educational Objective:''' <br/> '''References:''' OB/GYN Aditya Govindavarjhulla A 26 year old woman in her 16th week of pregnancy presents to the office for a routine pregnancy check-up. She gives a history of coming into contact with a 2 year old child who had German measles. At what time during her pregnancy is she at highest risk of transmitting the virus to the fetus to cause congenital rubella syndrome? B Obstetrics & Gynecology Pediatrics 2020-10-27T23:16:49Z 2459150.4700116 WBR0081