Transfer of blastocysts in human: Course and outcome of pregnancy and offspring

H.C. van Os, P.M. Rijnders and C.A.M. Jansen

Dept of IVF, Reinier de Graaf Group, loc Diaconessenhuis Voorburg, The Netherlands.

Introduction: Transfer of blastocysts in IVF is associated with a high implantation and pregnancy rate. We previously showed that when a sufficient number of embryos is available, a better selection can be made on day 5 instead of day 2 or 3, leading to a 40 % increase in success rate. However extension of the culture period may in itself impose new drawbacks and risks as at this stage the embryonic genome is activated, and there could be potentially negative influences between day 3 and day 5. It has been suggested in ruminants that the replacements of blastocysts and in-vitro maturation are associated with an increase in the incidence of the large calf syndrome. We therefore analyzed all pregnancies and children born after the replacement of blastocysts.

Methods: All ongoing pregnancies as a result of a transfer of day 5 embryos between May 1995 and March 1997 were followed up until after birth. Preferably, a pediatrician performed a physical examination after birth. We analyzed all ongoing pregnancies regarding the duration of gestation, birth weight, number of children, method of delivery and complications. All data were registered and included in a database All data are mean ± SD.

Results The age of the women that became pregnant was 33.4 ± 3.7 years.; infertility duration was 5.4 ± 3.1 years. In this period 75 pregnancies occurred after the transfer of day 5 embryos: 5 ectopic pregnancies (6,7 %) 14 first trimester abortions (18.7 %), and 56 ongoing pregnancies. There were 36 singletons, 19 twins and one triplet. Three pregnancies ended in a second trimester abortion: one induced because of herniation of the diaphragm, and two because of infections, none of them resulting in live offspring. These pregnancies were excluded form further analysis.

                                                                Singleton             Twins             Triplet

No of pregnancies                                       36                     19                 1

No of second trimester abortions                     2                   1                 0

No of living children                                       34                 35                 3

Mean ± SD duration of gestation (weeks) 39.9 ± 1.1             36.1 ±2.0      34.4

Mean ± Birth Weight (g)                         3428 ± 494   2449 ± 501 2120 ±204

Vaginal Births/ Caesarean Sections             27/ 7               12/ 6                 0/ 1

All but one child were examined by a pediatrician. There was one major congenital abnormality at birth (1.4 %): aplasia of the left fore- arm. All other babies appeared healthy. The incidence of abnormalities was within the normal range reported for IVF as well as the range for natural fecundity. A follow up after at least 2 years is still pending.