Clinical Review

2023 Update on obstetrics

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References

Managing pregnancies that result from IVF

Society for Maternal-Fetal Medicine (SMFM); Ghidini A, Gandhi M, McCoy J, et al; Publications Committee. Society for Maternal-Fetal Medicine consult series #60: management of pregnancies resulting from in vitro fertilization. Am J Obstet Gynecol. 2022;226:B2-B12.

Assisted reproductive technology contributes to 1.6% of all infant births, and although most pregnancies are uncomplicated, some specific risks alter management.5–7 For example, IVF is associated with increased rates of prematurity and its complications, fetal growth restriction, low birth weight, congenital anomalies, genetic abnormalities, and placental abnormalities. In addition, there is doubling of the risk of morbidities to the pregnant IVF patient, including but not limited to hypertensive disorders and diabetes. These complications are thought to be related to both the process of IVF itself as well as to conditions that contribute to subfertility and infertility in the first place.

Genetic screening and diagnostic testing options

IVF pregnancies have a documented increase in chromosomal abnormalities compared with spontaneously conceived pregnancies due to the following factors:

  • karyotypic abnormalities in couples with infertility
  • microdeletions on the Y chromosome in patients with oligospermia or azoospermia
  • de novo chromosomal abnormalities in IVF pregnancies that utilize intracytoplasmic sperm injection (ICSI)
  • fragile X mutations in patients with reduced ovarian reserve
  • imprinting disorders in patients with fertility issues.

A common misconception is that preimplantation genetic testing renders prenatal genetic screening or testing unnecessary. However, preimplantation testing can be anywhere from 43% to 84% concordant with prenatal diagnostic testing due to biologic and technical factors. Therefore, all pregnancies should be offered the same options of aneuploidy screening as well as diagnostic testing. Pretest counseling should include an increased risk in IVF pregnancies of false-positives for the first-trimester screen and “no-call” results for cell-free fetal DNA. Additionally, diagnostic testing is recommended specifically in cases where mosaic embryos are transferred when euploid embryos are not available.

Counseling on fetal reduction for multifetal pregnancies

The risks of multifetal pregnancies (particularly higher order multiples) are significant and well documented for both the patient and the fetuses. It is therefore recommended that the option of multifetal pregnancy reduction be discussed, including the risks and benefits of reduction versus pregnancy continuation, timing, procedural considerations, and genetic testing options.5,8

Detailed anatomic survey and fetal echocardiogram are indicated

Fetal anomalies, including congenital cardiac defects, occur at a higher rate in IVF pregnancies compared with spontaneously conceived pregnancies (475/10,000 live births vs 317/10,000 live births). Placental anomalies (such as placenta previa, vasa previa, and velamentous cord insertion) are also more common in this population. A detailed anatomic survey is therefore recommended for all IVF pregnancies and it is suggested that a fetal echocardiogram is offered these patients as well.

Pregnancy management and delivery considerations

Despite an increased risk of preterm birth, preeclampsia, and fetal growth restriction in IVF pregnancies (odds ratios range, 1.4–2), serial cervical lengths, serial growth ultrasound exams, and low-dose aspirin are not recommended for the sole indication of IVF. Due to lack of data on the utility of serial exams, a single screening cervical length at the time of anatomic survey and a third-trimester growth assessment are recommended. For aspirin, IVF qualifies as a “moderate” risk factor for preeclampsia; it is therefore recommended if another moderate risk factor is present (for example, nulliparity, obesity, or family history of preeclampsia).9

There is a 2- to 3-fold increased risk of stillbirth in IVF pregnancies; therefore, antenatal surveillance in the third trimester is recommended (weekly starting at 36 weeks for the sole indication of IVF).10 As no specific studies have evaluated the timing of delivery in IVF pregnancies, delivery recommendations include the option of 39-week delivery with shared decision-making with the patient.

WHAT THIS EVIDENCE MEANS FOR PRACTICE
While the expected outcome is good for most pregnancies conceived via IVF, there is an increased risk of adverse perinatal outcomes that varies based on individual patient characteristics and IVF technical aspects. Individualized care plans for these patients should include counseling regarding genetic screening and testing options, multifetal reduction in multiple gestations, imaging for fetal anomalies, and fetal surveillance in the third trimester.

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