Normal Twin Pregnancies Research Articles

Morphological development of the human placenta in normal and complicated gestation: a quantitative and ultrastructural study.

In order to evaluate the structural potentialities of the placenta, we analyzed placentas in the following conditions: normal full term gestation, hypertensive status, twin pregnancy and abortion at 8-12 weeks of gestation, comparing cell structures, surface organization and tissue reaction. We quantitatively evaluated (1) the arborization of the placental villous tree, and (2) the microvillous density per unit of surface area, paralleling these data with ultrastructural and immunohistochemical features. In early gestation (8-12 weeks of pregnancy) the limited degree of branching of placental villi parallels a reduced number of clefts per unit of surface area (0.7/1,000 microns2), if compared with controls (2.7/1,000 microns2). In the full term twin placenta, the number of furrows is 2.26/1,000 microns2: this value reflects a low arborization potentiality, testifying to a low placental maturity. On the contrary, a high branching of the placental villous tree is present at term in hypertension. In this gestational condition, the number of sulci of 3.1/1,000 microns2 reveals a compensatory attitude of the placenta, aiming to sustain the impaired fetal-maternal metabolic interchange. In all these cases, syncytiotrophoblastic microvilli are reduced in number in comparison with the normal placenta, and this is likely to be an expression of a low trophoblastic maturation degree. The placenta is a barrier with a highly specialized function that conditions fetal outgrowth, and microenvironmental modifications are promptly faced by this structure through morphofunctional modulations.

Placental protein 10 (PP10) in singleton and twin pregnancy complicated by pre-eclampsia.

Circulating levels of placental protein 10 (PP10) were measured by radioimmunoassay in 140 women with normal singleton pregnancy (140 samples), in 6 women with normal twin pregnancy (15 samples) and in 35 pregnant women with pre-eclampsia (51 samples from singleton pregnancies and 7 samples from twin pregnancies) between 24 and 40 weeks. In singleton pregnancies with pre-eclampsia, the levels were lower than normal (P less than 0.01). In twin pregnancy the circulating PP10 levels were not significantly affected. These results suggest that changes in placental function are reflected in the circulating PP10 levels.

Ultrasonographical evaluation of the incidence of simultaneous and independent movements in twin fetuses.

Fetal movements (FM) may be spontaneous, originating in the fetus itself, or evoked by external stimuli. The relative rate of spontaneous and evoked FM has not yet been documented. As it is impossible to differentiate in a singleton pregnancy between these types of movements - the natural model of twin pregnancy was used. The FM of 10 normal twin pregnancies between 33 and 39 weeks of gestation were studied by two realtime ultrasounds, and were operated by two ultrasonographers over a period of 10 min. The mean number of independent FM of each fetus which occurred while the other fetus was resting was 7.9 FM and 7.7 FM, respectively (average 7.8 FM). A mean of 2.5 FM occurred simultaneously. The rate of independent FM was 75.7% and that of simultaneous FM was 24.3%. Vibroacoustic stimulation applied to the maternal abdomen evoked simultaneous movements of both fetuses in all cases. It is suggested that the independent FM may represent spontaneous FM and that the simultaneous FM may indicate the presence of an external stimuli and are therefore evoked responses.

Placental protein and hormone measurements in twin pregnancy.

Maternal serum levels of human placental lactogen (hPL), schwangerschaftsprotein 1 (SP1), pregnancy-associated plasma protein A (PAPP-A), placental protein 5 (PP5) and total oestriol (E3) were measured serially in 35 twin pregnancies during the third trimester. Eighteen pregnancies had major complications including dysmaturity of one or both fetuses in nine, premature labour in six, and placental abruption in three. Serum levels of all five variables were higher than in singletons, this distinction being greatest for hPL and lowest for SP1 and E3. The levels of hPL, PP5 and E3 just before delivery were significantly correlated with the total birthweight, a correlation with placental weight being evident only for hPL and PP5. A significant correlation between the five biochemical variables at 33-34 weeks was only seen between hPL and PAPP-A. Protein and hormone levels in the abnormal twin pregnancies were not apparently different from those in the normal twin pregnancies. These data suggest that only hPL levels biochemically reflect this extreme of fetal and placental growth, but that neither the levels of hPL nor any of the other biochemical indices examined are altered in abnormalities in twin pregnancy.

Twin pregnancy: routine use of ultrasound examinations in the prenatal diagnosis of intrauterine growth retardation and discordant growth.

A prospective study was undertaken in 42 normal twin pregnancies to determine the value of routine ultrasound evaluation in the prenatal diagnosis of intrauterine growth retardation (IUGR) and intra-pair growth discordancy in twin gestations. Use of multiple sonographic parameters significantly improved diagnostic accuracy when compared with the use of single parameters, such as biparietal diameter (BPD) alone in the prepartum diagnosis of these two entities.

Circulating beta-2-microglobulin levels during pregnancy and their possible relationship with feto-maternal histocompatibility.

Plasma beta 2 microglobulin (beta 2m) levels have been measured by radioimmunoassay in normal pregnant women, in two successive pregnancies of a woman who shares HLA antigens with her husband, in normal twin pregnancies, in toxemic pregnancies and in hydatidiform moles. During normal pregnancy, plasma beta 2m levels decrease reaching a minimum at week 14 and increase thereafter to a maximum at week 34. In the two successive pregnancies of the one patient with HLA compatibility, beta 2m concentrations were significantly lower than in normal pregnancies. Women with monozygotic twins had significantly less beta 2m than women with heterozygotic twins. Toxemic patients bearing female fetuses had also statistically lower beta 2m levels than toxemic women with male fetuses. Patients suffering from hydatidiform moles had beta 2m levels in the range of normal pregnant patients. Since circulating beta 2m is produced by lymphocytes one might assume that low beta 2m levels reflect a reduced activity of lymphocytes. The results presented here allow to propose a hypothesis which will have to be verified that reduced beta 2m levels are associated with an increased feto-maternal histocompatibility.

Unconjugated estradiol, estriol and total estriol in maternal peripheral vein, cord vein, and cord artery serum at delivery in pregnancies with intrauterine growth retardation.

The levels of unconjugated estradiol (E2), estriol (E3) and total (conjugated plus unconjugated) E3 in maternal vein serum during labor, cord vein serum, and cord artery serum were measured in normal singleton and twin pregnancies with appropriate for dates babies (AFD) and with light for dates babies (LFD). The mean level of total E3 in the maternal vein serum in singleton pregnancy was significantly lower in the LFD group than in the AFD group, but no differences were seen in the mean levels of unconjugated E2 or E3 between the groups. The concentration of unconjugated E2 in the maternal vein serum was significantly higher in the twin group with a large placenta than in the singleton group with a smaller placenta, while the concentration of total E3 in the case of twin pregnancy with LFD was lower than that in singleton pregnancy with AFD but not significantly. No difference in the concentration of total E3 was observed between the cord vein serum and cord artery serum. The present data suggest that the total E3 level in maternal vein serum may be used in evaluating fetal states such as intrauterine growth retardation.

Serum concentrations of human chorionic gonadotrophin and its alpha and beta subunits. 1. During normal singleton and twin pregnancies.

Homologous radioimmunoassays have been developed for native hCG and its alpha and beta subunits. Their specificities were assessed by analysis of the inhibition ca and beta subunits. 1. During normal singleton and twin pregnancies.

Sonar cephalometry in twins: A table of biparietal diameters for normal twin fetuses and a comparison with singletons

In 123 normal twin pregnancies, 589 biparietal diameter (BPD) measurements were obtained between 16 and 40 weeks' gestation and mean values for each week were computed. A table of BPDs for normal twin pregnancies based on these data is proposed. Mean twin BPDs were consistently smaller than those of singletons, the difference averaging 3.5 mm between 16 and 40 weeks' gestation. The development of a twin BPD table now permits a more accurate assessment of twin gestational age and fetal growth.

THE CAUSE OF THE FALL IN SERUM FOLATE IN NORMAL PREGNANCY

Study of a complete antenatal population, a group of normal primigravid singleton pregnancies, and a group of normal twin pregnancies, suggests that the fall in the serum folate concentration which occurs in normal pregnancy is due principally to plasma volume expansion and should therefore be regarded as physiological.

Pre-eclampsia in pregnancies by different fathers: immunological studies.

Immunological studies were performed on a woman with severe pre-eclamptic toxaemia in a second pregnancy. This pregnancy followed a normal twin pregnancy by a different father four years earlier. Both fathers were also studied. In the mixed lymphocyte culture the patient's lymphocytes reacted eight times as strongly against father 2's cells as against those from father 1. If studies along these lines are performed when a women has toxaemic and non-toxaemic pregnancies by different fathers information may be obtained on immunogenetic aetiological factors which may be of more value than that derived from the study of large unselected populations.

Maternal metabolic response to twin pregnancy in primigravidae.

SummaryIn normal primigravid twin pregnancies the plasma volume and red cell volume are greater than in singleton pregnancies; the total protein concentration is lower but the intravascular protein mass is the same; urinary oestriol excretion is higher. The body weight is greater but the total body water is the same, suggesting that there is more fat storage in twin pregnancies. There is no difference in serum sodium, potassium, chloride, non‐protein nitrogen or osmolality between singleton and twin pregnancies.

Serum L-leucyl-beta-naphthylamide hydrolase activity in normal single and twin human pregnancies and in pregnancies associated with fetal dysmaturity.

Serum L-leucyl-beta-naphthylamide hydrolase activity in normal single and twin human pregnancies and in pregnancies associated with fetal dysmaturity.

Lutein cysts in normal twin pregnancy leading to erroneous diagnosis of hydatid mole: A case report

A report is presented of a case of twin pregnancy in which there were many signs and symptoms and clinical laboratory findings commonly associated with the presence of either a hydatidiform mole or a chorionepithelioma, but there was no evidence found in the uterus or its contents of either of these two diseases.