Early amniocentesis: a clinical review

Drug exposure during pregnancy: Current understanding and approaches to measure maternal-fetal drug exposure

Prescription drug use is prevalent during pregnancy, yet there is limited knowledge about maternal-fetal safety and efficacy of this drug use because pregnant individuals have historically been excluded from clinical trials. Underrepresentation has resulted in a lack of data available to estimate or predict fetal drug exposure. Approaches to study fetal drug pharmacology are limited and must be evaluated for feasibility and accuracy. Anatomic and physiological changes throughout pregnancy fluctuate based on gestational age and can affect drug pharmacokinetics (PK) for both mother and fetus. Drug concentrations have been studied throughout different stages of gestation and at or following delivery in tissue and fluid biospecimens. Sampling amniotic fluid, umbilical cord blood, placental tissue, meconium, umbilical cord tissue, and neonatal hair present surrogate options to quantify and characterize fetal drug exposure. These sampling methods can be applied to all therapeutics including small molecule drugs, large molecule drugs, conjugated nanoparticles, and chemical exposures. Alternative approaches to determine PK have been explored, including physiologically based PK modeling, in vitro methods, and traditional animal models. These alternative approaches along with convenience sampling of tissue or fluid biospecimens can address challenges in studying maternal-fetal pharmacology. In this narrative review, we 1) present an overview of the current understanding of maternal-fetal drug exposure; 2) discuss biospecimen-guided sampling design and methods for measuring fetal drug concentrations throughout gestation; and 3) propose methods for advancing pharmacology research in the maternal-fetal population.

Targeted drug delivery for maternal and perinatal health: Challenges and opportunities

Pre-existing conditions at reproductive age, and complications arising during pregnancy can be detrimental to maternal and fetal health. Current therapies to combat obstetric disorders are limited due to the inherent complexity of pregnancy, and can have harmful effects on developing fetus. Emerging research shows intricate signaling between the cells from mother and fetus at maternal-fetal interface, providing unique opportunities for interventions specifically targeted to the mother, fetus, or placenta. Advancements in nanotechnology, stem-cell biology and gene therapy have resulted in target-specific treatments with promising results in pre-clinical maternal and fetal disorder models. Comprehensive understanding of the effect of physicochemical properties of delivery systems on their uptake, retention and accumulation across placenta will help in the better diagnosis and treatment of perinatal disorders. This review describes the factors leading to obstetric complications along with their effect on pregnancy outcomes, and discusses key targeted therapeutic strategies for addressing conditions related to maternal and fetal health.

Genetics: update on prenatal screening and diagnosis

There have been tremendous advances in the ability to screen for the "odds" of having a genetic disorder (both mendelian and chromosomal). With microarray analyses on fetal tissue now showing a minimum risk for any pregnancy being at least 1 in 150 and ultimately greater than 1%, it is thought that all patients, regardless of age, should be offered chorionic villus sampling/amniocentesis and microarray analysis. As sequencing techniques replace other laboratory methods, the only question will be whether these tests are performed on villi, amniotic fluid cells, or maternal blood.

Invasive prenatal diagnostic procedures 2005

Amniocentesis and Chorionic Villus Sampling have been the two most common prenatal diagnostic procedures for decades. There are wide variations in utilization, operator skills, quoted procedure risks, actual observed risks, and patient choices that come from highly variable counseling as to those risks. The compilation of published data suggests procedure risks of amniocentesis to be about 1/200 and in very skilled hands to be slightly lower. The risks of CVS in very experienced hands may also be about 1/200. Most studies comparing CVS to amniocentesis in skilled hands have found equivalency of risks. No well controlled studies support claims of amniocentesis risk at 1/1000 or lower. There is no increased risks of limb reduction defects following CVS at 10 weeks or greater, but there is an increase in Talipes from "Early Amniocentesis." In the first trimester CVS is the safer procedure.

A report of early (13 + 0 to 14 + 6 weeks) and mid-trimester amniocenteses: 10 years' experience

OBJECTIVE

To report in singleton pregnancies the post-procedure safety and maternal complications of early amniocenteses performed between 13 + 0 and 14 + 6 weeks of gestation and mid-trimester amniocenteses performed between 15 + 0 and 18 + 6 weeks of gestation.

METHODS

The study was carried out at the Prenatal Diagnosis Center, Siena University, Italy, during a 10-year period, following the Regional Protocol for Prenatal Diagnosis. Our study population included 3769 amniocenteses, 475 early and 3294 mid-trimester. Complications considered included miscarriage (immediately after the procedure and until 24 weeks of gestation), blood-stained amniotic fluid, failed cell culture, amniotic fluid leakage, preterm premature rupture of the membranes (PROM), preterm delivery and presence of neonatal talipes equinovarous.

RESULTS

Cytogenetic anomalies were found in 111 cases (2.9%), 18 occurring early and the other 93 in mid-trimester. Miscarriage occurred in two cases in the early amniocentesis group (0.4%) and in ten cases among the mid-trimester group (0.3%). The overall loss of pregnancies due to amniocentesis in this study was 0.3%. Amniotic fluid was stained in 1.2% in the early group and 0.9% in the mid-trimester group. Amniotic fluid leakage was noted in 1.4% and 1.2%, preterm PROM was noted in 3.3%) and 3%, and preterm delivery occurred in 8% and 7.6%, respectively. There were no cases of failed amniotic culture and no cases of talipes equinovarous documented.

CONCLUSIONS

The risks of early amniocentesis performed between 13 + 0 and 14 + 6 weeks appear to be comparable to those of mid-trimester amniocentesis and thus early amniocentesis could be offered to the parents, as an alternative to chorionic villus sampling, in order to obtain cytogenetic results earlier in pregnancy without a significantly increased risk for both mother and fetus. Further operators' experience with the method, based on long and accurate follow-up, and further studies are necessary to assess the safety of the method.

First trimester prenatal diagnosis: amniocentesis

Twenty years after midtrimester genetic amniocentesis was first used, first trimester invasive prenatal procedures were introduced. Chorionic villous sampling presents some disadvantages that entitled many centers to look into an alternative for first trimester diagnosis. Early amniocentesis (EA) can be performed effectively, as shown over the years in many observational studies and partially randomized and randomized trials. Recently, a multicenter randomized trial (Canadian Early and Midtrimester Amniocentesis Trial) reported a higher total pregnancy loss, a significant increased incidence of musculoskeletal foot deformities, a significant increased culture failure rate, and an increased postamniocentesis rate of leakage in the EA group compared with midtrimester amniocentesis. These results concerning EA procedures from 11w(+0) to 12w(+6) should be included in any pre-EA counseling. However, further trials have started to evaluate EA procedures between 13w(+0) to 14w(+6).

Prenatal screening and women's perception of infant disability: a Sophie's Choice for every mother

Prenatal screening can significantly benefit parents and the community. However, it has created a dilemma for women as it requires them to quickly decide whether to continue a pregnancy or terminate it should the test indicate a foetal abnormality. This can be psychologically traumatic for women torn between their connection to an unborn child with all its possible imperfections, and a desire to prevent its suffering as a disabled child in later life. A woman must also consider her own and her family's future welfare. Extensive research into the physical aspects of prenatal screening has not explored the meaning of the experience for women or whether termination is the most appropriate option. This article examines recent qualitative studies, concluding that women who terminate a pregnancy following prenatal screening may experience an acute grief reaction or be plagued by guilt and fear that can precipitate marital breakdown. Additionally, there is a risk that through striving to eradicate congenital disability, a community risks promoting a cult of perfectionism that may have discriminatory effects on disabled people.

Women's opinions and the implications of first- versus second-trimester screening for fetal Down's syndrome

Two groups of pregnant women were questioned regarding their opinions on serum screening for Down's syndrome in the first trimester of pregnancy. One group comprised 83 women attending our antenatal clinic who were questioned at the time of the existing second-trimester screening test. Seventy-six per cent of those who participated in the second-trimester screening programme would have preferred the test to have been in the first trimester, mainly because of the easier termination of pregnancy and/or the earlier reassurance provided. The remaining 24 per cent could see no advantage in the earlier time frame. Of the 49 women who had declined second-trimester screening, only two would have participated in screening had it been in the first trimester. The other group comprised those women attending our antenatal diagnosis clinic who were considering chorionic villus sampling (CVS). Forty-four per cent of these women would have allowed serum screening in the first trimester to influence their decision as to whether to undergo definitive prenatal diagnostic testing. In general, those women who made use of second-trimester serum screening would also do so in the first trimester. Those who declined the existing screening programme would also decline first-trimester screening. Many women currently deciding to undergo CVS would allow a first-trimester screening test to influence their decision.