Preclinical abortions: incidence and significance in the Norfolk in vitro fertilization program

Role of embryo quality in predicting early pregnancy loss following assisted reproductive technology

Early pregnancy loss (EPL) significantly reduces the initial success rate of assisted reproduction treatments and increases the psychological burden on the patient. The aim of the current study was to investigate the association between embryo quality and EPL in IVF. A retrospective study of 1471 women undergoing IVF between July 2000 and October 2004 was performed. Multivariate logistic regression models evaluated the effect on EPL of the woman's age, type and cause of infertility, endometrial thickness on the day of oocyte retrieval, performance of intracytoplasmic sperm injection, number of transferred embryos, embryo quality as assessed by the number of blastomeres in the leading transferred embryo at day 3, and the percentage of fragmentation. The 2902 oocyte retrieval-embryo transfer cycles resulted in 816 pregnancies (28.1%; 705 women) constituting the study cohort. Of these, 259 pregnancies (31.7%) ended in EPL and 557 (68.3%) in ongoing pregnancies. EPL risk was significantly associated with advanced (>35 years) maternal age (OR=1.53; 95% CI 1.12-2.09) and five or fewer blastomeres in the leading embryo transferred at day 3 (OR=1.82; 95% CI 1.16-2.85). In conclusion, the quality of transferred embryos, as assessed by the total number of blastomeres in the leading transferred embryo, and maternal age are predictors of EPL.

Early pregnancy loss in in vitro fertilization (IVF) is a positive predictor of subsequent IVF success

OBJECTIVE

To determine the significance of biochemical pregnancy losses and clinical spontaneous abortion (SAB) on outcomes of future IVF cycles.

DESIGN

Retrospective cohort study.

SETTING

Academic IVF program.

PATIENT(S)

Women with a history of unsuccessful IVF attempts undergoing IVF.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate.

RESULT(S)

Patients with an early pregnancy loss had a greater ongoing clinical pregnancy rate in the immediate next cycle when compared with those women who had a negative pregnancy test (37.3% vs. 27.3%). Patients with a history of a biochemical pregnancy or a clinical spontaneous abortion had an ongoing clinical pregnancy rate in the next cycle of 38.4% and 42.3%, respectively, compared with 27.3% in women who had a history of a negative pregnancy test. The cumulative pregnancy rate after the first IVF attempt was 54.1% in patients with a previous biochemical pregnancy loss, 61.4% in those with a previous clinical SAB, and 46.5% in women with a previous negative pregnancy test.

CONCLUSION(S)

Women who experience an early pregnancy loss after IVF have a greater likelihood of success in subsequent IVF cycles when compared with patients who fail to conceive.

What is a preclinical pregnancy loss?

PURPOSE

To evaluate the contribution of embryo quality to preclinical loss rates after in vitro fertilization (IVF)/embryo transfer (ET) pregnancy, multiple gestation, and clinical loss rates were compared to preclinical pregnancy loss rates over a 3-year period.

METHODS

The pregnancy outcomes after 1675 fresh ETs from 1994 to 1997 were studied. While establishment of a clinical pregnancy confirms uterine receptivity, multiple gestation rates reflect embryo quality. Because the majority of clinical losses are chromosomally abnormal, clinical loss rates serve as another indicator of embryo quality.

RESULTS

The overall preclinical pregnancy loss rate was 5% (78/1675) of ETs and 17% (78/472) of pregnancies. During the 3-year period the pregnancy rates per ET increased from 19 to 36% (P < 0.0001), multiple gestation rates increased from 21 to 48% (P < 0.008), clinical loss rates decreased from 20 to 6% (P < 0.0001), and preclinical pregnancy loss rates remained unchanged from 13 to 19% (P = 0.1).

CONCLUSIONS

Preclinical pregnancy loss more likely reflects abnormalities in uterine receptivity rather than embryo quality. If recurrent preclinical pregnancy loss occurs after IVF/ET, evaluation for abnormalities of uterine receptivity should be performed.

Infertility and early pregnancy loss

OBJECTIVES

We describe the epidemiologic characteristics of conception, including subclinical early pregnancy loss, in a population of healthy women volunteers who had heterogeneous fertility experiences, and we describe the conception experience of women within this group who had evidence of impaired fertility.

STUDY DESIGN

This was a prospective observational study of a cohort of women employed in two semiconductor manufacturing facilities. A total of 148 volunteers completed interviews and daily diaries and collected daily urine specimens for an average of 7 months. Conception, including subclinical losses and clinical pregnancies, was determined with a highly sensitive and specific assay for urinary human chorionic gonadotropin, and ovulation was determined with assays of urinary ovarian steroid hormones.

RESULTS

There were 679 menstrual cycles at risk for pregnancy contributed by 124 (84%) of the 148 women. Women with evidence of subfertility before or during the study period had a rate of early pregnancy loss of 70% compared with 21% in women without fertility problems (relative risk 2.6, 95% confidence interval 1.8 to 3.8). The risk of pregnancy loss associated with subfertility increased with age and remained the same in women treated with clomiphene citrate.

CONCLUSIONS

These results suggest that subfertile women have increased subclinical pregnancy losses regardless of fertility treatment and that the association between reduced fertility and advancing age may be related, in part, to early subclinical pregnancy loss.

The predictive value of a single beta human chorionic gonadotropin in pregnancies achieved by assisted reproductive technology

OBJECTIVE

To investigate whether a single serum beta-hCG in pregnancies achieved by assisted reproductive technologies (ART) can accurately predict pregnancy viability and, in viable pregnancies, multiple gestation.

DESIGN

Four hundred sixty-one consecutive successful ART pregnancies were studied retrospectively. Seventy-one of the 461 patients were excluded because their beta-hCG was either drawn on the incorrect day or outside our facility. Three hundred ninety subjects had a serum beta-hCG drawn 14 days after ET or 16 days after gamete transfer. The beta-hCG samples were analyzed by immunoradiometric assay based on the Third International Reference Standard (IRS) (First International Reference Preparation (IRP)). Pregnancy status was followed, at minimum, through the first trimester.

RESULTS

One hundred fifty (38%) of the 390 were found to be nonviable, resulting in spontaneous abortion (n = 38, 10%), ectopic pregnancy (n = 27, 6%), or biochemical pregnancies (n = 85, 22%). A statistically significant difference by the Scheffe F-test was found between the mean beta-hCG value of the nonviable (115 mIU/mL) (conversion factor to SI unit, 1.00) and viable (428 mIU/mL) pregnancies. The positive predictive value of a single beta-hCG > 100 mIU/mL in distinguishing viable from nonviable pregnancies was 0.83 (sensitivity 91%, specificity 71%). Of the 240 viable pregnancies, 74 (32%) were multiple gestations (57 twins, 14 triplets, and 3 quadruplets). The mean beta-hCG of the singleton pregnancies (266 mIU/mL) was significantly different from that of the multiple gestations (792 mIU/mL). The positive predictive value of a single serum beta-hCG < or = 400 mIU/mL in distinguishing singleton from multiple gestations was 0.92 (sensitivity 86%, specificity 82%).

CONCLUSION

A single early serum beta-hCG may be used in ART pregnancies to predict which pregnancies will continue beyond the first trimester and to identify multiple gestations. Early reassuring tests may reduce anxiety.

Effect of paternal leukocyte immunization on implantation after biochemical pregnancies and repeated failure of embryo transfer

PROBLEM

It is unclear how paternal leukocyte immunization prevents pregnancy loss. We investigated whether immunization affects early pregnancy, and whether it increases the rate of implantation and early embryonic development at the time of implantation.

METHOD

Three groups of women with possible implantation failure were immunized: (1) recurrent biochemical pregnancies (> 3), (2) three or more failed in vitro fertilization (IVF) cycles, and (3) IVF after immunization for recurrent abortion (> 3). Patients were immunized if antipaternal complement-dependent antibody (APCA) was negative, and mixed lymphocyte culture hyporeactive to husbands lymphocytes. Immunizations were prepared from 100 ml paternal blood separated by Ficoll Hypaque density centrifugation. IVF was attempted after APCA was produced.

RESULTS

In the women with biochemical pregnancies, 10 to 12 subsequent pregnancies developed normally. Seventy-nine subsequent IVF cycles in 33 patients resulted in 20 pregnancies, 16 of which developed normally. Six pregnancies followed 30 cycles in recurrent failed IVF, and 14 pregnancies from 49 cycles in 23 patients with previous habitual abortion.

CONCLUSIONS

This treatment may prevent further biochemical pregnancies if control studies confirm this preliminary observation, but was not shown to affect recurrent failed embryo transfer.

The prognostic value and significance of preclinical abortions in in vitro fertilization-embryo transfer programs

Preclinical abortions occur in natural conceptions as well as in in vitro fertilization-embryo transfer (IVF-ET) cycles. Nevertheless, although known, this entity is ill defined.

OBJECTIVE

The purpose of this study was to propose a classification of these pregnancies on the basis of pathophysiological evidence and to evaluate their future clinical impact.

DESIGN

Of 970 IVF-ET cycles, 114 cycles (11.7%) terminated in preclinical abortions. Abortions were divided according to peak beta human chorionic gonadotropin (beta-hCG) values into chemical abortions (52%) occurring 2 weeks after ET with beta-hCG values not higher than 21 mIU/mL and peri-implantation abortions (47%) terminating spontaneously 4 weeks after ET; the latter had higher beta-hCG values for a longer period of time but without any sonographic evidence of gestational sac. No woman in the two groups needed curettage.

RESULTS

After a chemical abortion, the pregnancy outcome had better ongoing pregnancy rates (24.7%) in comparison with the 17% achieved in the total IVF-ET cycles.

CONCLUSIONS

It is concluded that these two groups most probably have different pathophysiological backgrounds and concomitantly different future clinical impacts.