Preliminary investigations on the psychomotor development of infants from multiple pregnancies have been carried out.

The psychomotor development in the first six months of life appears to he more similar in MZ than DZ twin partners. It further appears to be rather connected with birth weight than with birth order. The psychomotor development of twins with a birth weight exceeding 2300 g attains, as early as in the first six months of life, a level concordant with the standards established for singletons.

A total of 59 children from multiple pregnancy, aged from 18 months to 13 years, have all shown a mental development within or above normal limits.

In 18 children there are reasons to suspect the presence of a CNS lesion, although the general mental level is good.

The numerical concordance of intelligence quotients is not typical for MZ and DZ twins. In four cases there were marked qualitative differences despite IQ concordance.

The behavior of twins in their home, preschool, and school environment, is determined by the separate nature of the relationship in which the twins live since birth.

Psychological examinations were made in 56 children from quintuplet, quadruplet, and triplet pregnancies. The psychomotor development of these children from multiple pregnancies did not, as a rule, differ much from the one of singletons, although the multiple pregnancy was more inclined to cause lesions of the central nervous system. Out of the 56 children examined, 25 were found to develop properly.

It is necessary to examine the development of each child separately, taking into consideration its health condition in the neonatal period and its specific environment which effect the individual development and may be the cause of disturbances, as well as of mental differences not only in children from the same pregnancy but even in MZ twins.

The authors have examined 30 children from triplet pregnancies aged 18 months to 16.5 years. The group included 20 girls and 10 boys. Triplet pregnancy was found to be, in the average, the fourth consecutive pregnancy in mothers. Physical and mental development was assessed. It was found that 60% of children showed a physical development below the appropriate norm for their age. In 83% of the children under examination mental age ranged below chronological age.

The development of a total of 58 triplets, quadruplets, and quintuplets, born in the province of Danzig in the years 1957-1971, is analysed. The examinations show that the physical development of multiplets in the first year of age is similar to that of singletons, irrespective of their social conditions. In the second year of age, however, multiplets with bad social conditions showed a much worse rate of development.

Only half of the 56 children examined by a psychologist reached IQ norms, the others being on the verge of normalcy and mental deficiency, or even lower. Out of 30 school-age children, 16 had difficulties in learning and 15 of these showed features of mental development deficiency.

A 24-year-study has been made of female quadruplets, two homozygous and two heterozygous, delivered by Cesarean section at 36 weeks gestation to a gravida 2 with severe preeclampsia and hydramnios. The babies were small for gestational age.

The development, management, education, and social environment are described. All are above average height, and physical and emotional problems have been few. The intelligence and education attainment of the first (also the smallest) baby are in the superior range, the others were high average. Two girls have married, one of whom has two normal sons.

Four boys, born in 1954 as uniovular quadruplets, live in Wroclaw, Poland. This is a unique case in the world. Their uniovularity was proved as a result of serological analyses.

Despite the fact that one of the boys was seriously injured during the labor (he suffered from one-sided paresis and deafness) and lived in special conditions, all the boys are identical and they develop identically.

Genetic factors seem to be more important, in the shaping of the phenotype, than the influence of environment.

After listing the known cases of alive quintuplets, the authors describe the recent case of the Danzig quintuplets, with special respect to the medical care given during pregnancy, labor and Puerperium. Early diagnosis and hospitalization in cases of multiple pregnancies appear to be necessary, to overcome the tendency towards premature delivery and to secure relatively higher degree of maturity.

The morphological examination of the afterbirth of the Danzig quintuplets showed that it was composed of five fused placentas forming one single placenta, of extraplacental fetal membranes forming five separate fetal amniotic sacs and five umbilical cords. The structure of the placentas was very similar and no focal pathological changes were found in their texture. From a morphological point of view all separating membranes speak in favour of a quintovular pregnancy.

Blood groups of the Danzig quintuplets and their family were determined in order to establish whether they are mono- or polyzygotic in origin. Results of blood grouping showed that they come from a quintovular pregnancy. A pedigree of the quintuplets family is given. The following blood-group systems were tested: ABO, MN, Rh (Cw, C, c, D, E, e), Kell, haptoglobins, Gm1, and erythrocyte acid phosphatase.

The Danzig quintuplets were born in the 33rd week of pregnancy. Both the third and fifth child required treatment during the first 24 hours. During their stay in our clinic (81 days) all showed signs of dyspepsia and early anemia; two were treated for otitis media, and migrating convulsions were observed in one as a result of hyposaliemia. All the infants were discharged as healthy.

The level of immunoglobulins G, A, and M, were determined in the Danzig quintuplets using the method of single radial diffusion in the 5th, 6th, and 16th month of life. The IgG, IgM, and IgA level increased more slowly than in full-term healthy infants, but in the second year of life the level of IgG and IgM in the quintuplets corresponded already to normal values. The highest of IgG and IgM levels at the age of 16 months were found in the child with the lowest birth weight and in the children with most severe pneumonia in their first year of life.

The physical development of the quintuplets in their first year of age is described, including anthropological measurements, psychological, hematological, immunological, and other examinations.

Piotr appeared to show the highest rate of height and weight growth; Ewa, the lowest one. In the 7th month of age, head and chest circumference values achieved the standards of singletons born at term. Psychomotor development of the quintuplets was not only proper but even exceeding. Teething occurred in the 8th-10th month. Hematological examinations in the first 6 months showed some anemia, which disappeared in the 7th month. Other laboratory examinations did not show any deviations, except for slightly lowered serum level of gamma-globulins. In their first year of age the children suffered from nearly any diseases. The infections of the upper respiratory tract showed a mild course.

A psychological follow-up, based on the Brunet-Lézine Scale, showed a constant progress in the development of the quintuplets, the pace being quite proper from the 5th month on.

The children differed from each other: the best pace of psychomotor development was observed in Adam and Ewa, the worst in Piotr.

In all children, control of body posture showed the highest rate of development, exceeding the presumed norms. Some delay was observed in speech. The results of the examinations made by the Psyche-Cattell Intelligence Scale agree with those obtained by the Brunet-Lézine Scale.

Besides the differences in physical appearance, the children showed differences in personality features.

A total of 116 cases of multiple pregnancy has been observed in a 5-year period. MZ twin pregnancies appear to be significantly increased in the maternal age group 31-35. Also significant is the higher frequency of abnormal cycles in MZ twin pregnancies. Family incidence of twins is more significant in mothers of DZ as compared to MZ twins.

According to the data from the Danzig Institute of Obstetrics and Gynecology, among 69,100 deliveries in the years 1953-1972 there were 619 twins, 6 triplets, and 1 case of quintuplets. No multiple pregnancy was the result of hyperstimulation.

In the case of 100 women with primary sterility, treated also with clomiphene and gonadotropine, 67 pregnancies appeared and no case of multiple pregnancy was observed. No multiple pregnancy was observed in a sample of 50 women after discontinuing administration of hormonal contraceptives.

HCS, HCG, and HCG α and β subunits were measured in the serum of women with unifetal or multiple pregnancies. Highly specific radioimmunoassay procedures were used for the determinations.

Serum maternal levels of HCS are greatly increased in multiple pregnancies, sometimes more than could be expected from increased placental weight alone. Serum undissociated HCG is also elevated in multiple pregnancies. The relationship between undissociated HCG and its free circulating α and β subunits is different in multiple and unifetal pregnancies and this difference is discussed.

Radioimmunoassay of FSH and LH serum levels has been carried out on 15 Nigerian women, 6 of them mothers of singletons and 9 mothers of twins (2 of two sets). Higher FSH levels have been found in mothers of twins, which supports the view that a higher production of pituitary gonadotropins, resulting in a higher incidence of multiple ovulation, may be responsible for the higher incidence of twinning in Negro populations.

A statistical analysis has been carried out on the frequency of twin and triplet births in Poland in the years 1949-1971.

These frequencies appear to be higher than expected on the basis of Hellin's rule, there being 1 twin birth in 87 single births and 1 triplet birth in 118 twin births.

The share of MZ vs. DZ twins having been assessed through Weinberg's method, an analysis is carried out on maternal age, parity, and urban vs. rural environment. It is concluded that the frequency of polyovulation increases with parity, whereas it becomes reduced with age on account of menopause effect already at age 40.

The frequency of living twins born in Southern Moravia in the period 1960-1970 was studied and found to be 0.67%. No differences in twinning rate due to the years, seasons, districts or towns with 10,000 and more inhabitants in comparison with other localities, were found. An interesting hitherto undescribed phenomenon of twin-birth clustering in space and time was observed.