in a woman lasts for 40 weeks. It is divided into 3 trimesters. The first trimester of pregnancy is the stage when the vital organ structures of the fetus are formed; this is followed by the second and third trimester where the fetus grows and develops into a healthy baby. Exposure of the pregnant woman in the first trimester to certain infections, drugs or ionizing radiations may result in an abortion
or serious developmental malformations.
‘Exposure of the pregnant mother in the first trimester to certain infections, drugs or ionizing radiations may result in abortions or serious developmental malformations.’
Magnetic Resonance Imaging (MRI)
one of the imaging techniques is a useful tool for the diagnosis and evaluation of certain medical conditions. Women may undergo the investigation to diagnose certain disease conditions but the doctor may prefer to avoid it if he/she knows that the woman is pregnant. In such situations, awareness of the safety of the imaging technique prevents the unnecessary avoidance of such a useful tool in a pregnant woman.
Imaging techniques pose a risk to the developing fetus by exposing them to ionizing radiations or contrast agents used in the technique. Magnetic Resonance Imaging utilizes a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of the organs, soft tissues and other internal body structures. It is generally thought to be safe for the fetus in the second or third trimesters of pregnancy; however, its safety in the first trimester is not known due to absence of adequate controlled studies.
As per the recommendations of the American College of Obstetricians and Gynecologists' Committee on Obstetric practice:
- MRI is not associated with risk but should be used prudently.
- The use of gadolinium contrast with MRI should be limited and it may be used in pregnancy if it significantly improves the diagnostic performance and is expected to improve maternal or fetal outcome.
In the new study, Dr. Joel Ray, who is a physician and researcher at St. Michael's Hospital and an adjunct scientist at ICES, and colleagues used data from the Institute for Clinical Evaluative Sciences to examine the records of more than 1.4 million births in Ontario from 2003 to 2015. The children of women who had first-trimester MRIs were compared with those of women who had not undergone an MRI. The children were followed up till they completed 4 years of age.
The study documented the following findings:
- 1 in every 250 pregnant women in Ontario underwent an MRI at some point in their pregnancy.
- 1 in every 1,200 pregnant women had an MRI in the first trimester.
- A higher risk of stillbirth or neonatal death occurred in women who had a gadolinium-enhanced MRI, but the number of such events was few. The number of stillbirths in women undergoing gadolinium-enhanced MRI was documented to be as low as one in 50.
- A higher risk of a rheumatologic or skin condition was documented in children of women who had a gadolinium-enhanced MRI.
- The study does not include any specific information as to why the women received an MRI, or whether they knew they were pregnant at that time. The MRI was mainly requested by family physicians (44%), which suggests that the MRI may have been booked prior to the woman having conceived. Neurologists or neurosurgeons also commonly requested for MRI, suggesting that some women were investigated for headaches or spinal disc issues.
"Having an MRI at the earliest stages of pregnancy does not seem to alter the development of the fetus," said Dr. Ray. He also suggests that the results supported the clinical guidelines to avoid giving pregnant women gadolinium unless strongly indicated.