Maternal Age and Neonatal Development. Department of Normal Anatomy, Silesian Piasts University of Medicine in Wrocław, Poland 2

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1 ORIGINAL PAPERS Adv Clin Exp Med 2008, 17, 6, ISSN X Copyright by Silesian Piasts University of Medicine in Wrocław BOHDAN GWORYS 1, HENRYK KORDECKI 2, MARIA KNAPIK KORDECKA 3, ANDRZEJ KARMOWSKI 4 Maternal Age and Neonatal Development Wiek matki a rozwój noworodka 1 Department of Normal Anatomy, Silesian Piasts University of Medicine in Wrocław, Poland 2 Institute of Computer Science, Device and the Robotics, Wrocław University of Technology, Poland 3 Department and Clinic of Angiology, Arterial Hypertension and Diabetology, Silesian Piasts University of Medicine in Wrocław, Poland 4 First Department and Clinic of Gynecology and Obstetrics, Silesian Piasts University of Medicine in Wrocław, Poland Abstract Material and Methods. A group of 732 male and 758 female newborns was analyzed. Only first born neonates from singleton pregnancies born naturally and in very good condition (10 Apgar points) were included. Results. Statistical analysis showed that the mother s age during pregnancy had statistically significant influence on the newborn s wellness. Conclusions. Assuming that higher values of the metrical neonatal parameters indirectly indicate that their devel opment is close to optimal, it can be said that newborns delivered by teenage mothers had the lowest wellness level. This conclusion was valid for all the parameters investigated and depended neither on the newborn s sex nor preg nancy duration. This rule was more evident for body length and weight and less for the circumference parameters (Adv Clin Exp Med 2008, 17, 6, ). Key words: maternal age, neonate development. Streszczenie Materiał i metody. Analizie poddano 732 noworodki płci męskiej i 758 płci żeńskiej. Uwzględniono tylko nowo rodki, które pochodziły z pierwszej ciąży jednopłodowej, urodzone siłami natury i co do których nie było żadnych zastrzeżeń lekarskich (10 punktów w skali Apgar). W ten sposób autorzy chcą wykluczyć z badań wpływ rytmiki porodów, który mógłby wypaczyć uzyskane rezultaty, a w następstwie prowadzić do fałszywych wniosków. Noworodki bez klinicznych oznak wcześniactwa lub przenoszenia kwalifikowano jako normalne, niezależnie od tego, ile dni trwała ciąża. Wyniki. Wpływ wieku matki na zmienność cech metrycznych noworodka oceniano jednoczynnikową analizą wariancji, wykorzystując pakiet programów komputerowych Statistica Pl. Wnioski. Przeprowadzona analiza statystyczna upoważnia do stwierdzenia, że wiek matki w czasie ciąży i poro du wywiera znaczący (istotny statystycznie) wpływ na dobrostan nowo narodzonego dziecka. Jeżeli przyjmie się, że większe wartości cech metrycznych noworodka wskazują pośrednio na to, że jego rozwój jest bardziej zbliżony do rozwoju optymalnego, to należy stwierdzić, że najmniejszym dobrostanem cieszą się dzieci zrodzone z matek, które nie przekroczyły 20. roku życia. Taki wniosek nasuwa się po analizie wszystkich badanych cech, niezależnie od płci dziecka oraz długości trwania ciąży. Jest to bardziej widoczne w wartościach długości i masy ciała noworodka, słabiej w wartościach obwodu głowy. Zależność najmniej dotyczy wartości obwodu klatki piersiowej (Adv Clin Exp Med 2008, 17, 6, ). Słowa kluczowe: wiek matki, rozwój noworodka. Investigating neonatal body weight, Piasecki [1] found that the mother s age was closely related to the order of delivery. Partitioning according to the mother s age and delivery order, the author named three factors influencing the newborn s weight: the mother s age, the delivery order, and the regularity of deliveries connecting the delivery order with the mother s age. Many authors do not

2 650 B. GWORYS et al. take into account the delivery order when investi gating the influence of the mother s age and the results are therefore entirely different. Abdul Karim and Beydoun [2], Miller [3], and Bożiłow et al. [4] discovered no relationship between maternal age and the size of the fetus and newborn. However, Piasecki [1], Cieślik and Waszak [5], and Orkwiszewska and Gładykowska Rze czycka [6] discovered a statistically significant influence of this factor. The present authors believe that the dif ferences in these results were mainly caused by not taking into account the regularity ( rhythmici ty ) of deliveries. Studies on small numbers of newborns force the inclusion of first born as well as next born neonates. It is evident that a 20 year old mother cannot deliver six or seven newborns. The mother of six newborns would be at least 30. The aim of this paper was to evaluate newborn wellness according to their physical development in relationship to their mothers age at the time of delivery. It was assumed that wellness, determined by maximal comfort during prenatal development, allows the optimal use of genetic potential and paragenetic features in this period. As a result, the values of the investigated newborn parameters increase. Obviously, the higher the parameter val ues the better the wellness. Material and Methods Newborns born naturally at Silesian Piast University of Medicine, Wrocław, in the period of were investigated. The newborn group consisted of 732 males and 758 females. Only first borns from singleton pregnancies born natu rally and in very good condition (10 Apgar points) were included. In this way the influence of deliv ery rhythmicity on the results was eliminated. Newborns who were not premature or who were beyond term were also included in the group regardless of pregnancy duration. For each new born, body length, body weight, head circumfer ence, and chest circumference were measured. To eliminate the influence of newborn age, the group of newborns was divided into four sub groups. The three first percentiles were chosen as the subgroup boundaries. In this way four sub groups were obtained, with pregnancy periods of < 272, , , and > 288 days. Maternal age was analyzed in six groups, i.e. < 20, 20 23, 24 27, 28 31, 32 35, and > 35 years old. Each newborn had his/her own information card with the values of the analyzed parameters as well as all available clinical data related to the newborn and the mother. First the Kolmogorow Smirnow test was used to check if all the data samples were chosen from random variables with a normal distribution. In all cases the results were positive. The influence of maternal age on the variability of the neonatal parameters was checked using one way ANOVA. The differences between the average values of the newborns parameters were tested for the different maternal age groups. In this way statistically sig nificant differences were discovered and marked. All calculations were made with a significance level of α = Results The basic statistical parameters and the results of variance analysis are shown in Tables 1 4. Neonatal body length was closely related to the mother s age. Newborns with the smallest body length were delivered by mothers younger than 20. The physical development of these mothers was not yet completed. Newborns delivered by the old est mothers were a little longer, but the difference was not statistically significant. Newborns deliv ered by 20 to 27 year old mothers had the longest body lengths. Variance analysis showed statistical ly significant differences compared with other newborns. This tendency did not depend on the duration of pregnancy or the newborn s sex. Neonatal body weight had the same variabili ty as body length. The weights of newborns of young mothers were less than those of older moth ers. The differences were statistically significant. The differences in neonatal weight for mothers over 20 years old were not statistically significant. This rule was the same for males and females and did not depend on the duration of pregnancy. The variability in head circumference in the newborns was very similar to that in neonatal body mass. Newborns delivered by teenage mothers had smaller head circumferences those delivered by mothers over 20 years old. This rule was valid for both males and females. However, smaller differ ences were observed than those for neonatal length and weight. Statistically significant differences appeared only in newborns with a proper duration of pregnancy. This tendency was also observed in newborns from pregnancies of improper duration, but the differences in this case were not statistical ly significant. The differences were greater for males than for females. Chest circumference weakly correlated with the mother s age. No statistically significant dif ferences were discovered for any maternal age groups or for males or females. A small tendency similar to that observed above could be noted. Slightly lower values of this parameter could be observed for teenage mothers.

3 Maternal Age and Neonatal Development 651 Table 1. Variability of newborn body length according to the newborn s and mother s ages at delivery. Values which are significantly different are in bold Tabela 1. Zróżnicowanie długości ciała noworodków z uwzględnieniem ich wieku, płci oraz wieku matki w chwili porodu. Wartości zaznaczone czcionką pogrubioną są istotne statystyczne na poziomie α = 0, < 271 < < < < < < < > 289 < > < Discussion The results of the statistical analysis showed that the mother s age during pregnancy had a sta tistically significant influence on the newborn s wellness. Assuming that higher values of the met rical neonatal parameters indirectly indicate that their development is close to optimal, one can say that newborns delivered by teenage mothers had the lowest wellness level. This was valid for all the parameters investigated and depended neither on the newborn s sex nor pregnancy duration. This rule was more evident for body length and weight and less for the circumference parameters. There is no simple explanation for the influ ence of the mother s age. It seems that Thomp son s suggestion [7] that physiological uterus capacity changes depending on pregnancy time should be taken into account. The longer the preg nancy time, the greater the uterine plasticity and flexibility. Abdul Karim and Beydoun [2] stated that in the last trimester, when development is faster and the fetus linear dimensions are consid erably increasing, the uterus is not able to follow this progress. In this period the comfort of the inter uterine environment decreases and wellness is much lower. As a consequence, a lowering of perinatal fetal growth appears. This process is much more profound in teenage mothers in whom the developmental process is not yet finished and therefore newborns delivered by mothers younger

4 652 B. GWORYS et al. Table 2. Variability of neonatal body weight according to the newborn s and mother s ages at delivery. Values which are significantly different are in bold Tabela 2. Zróżnicowanie masy ciała noworodków z uwzględnieniem ich wieku, płci oraz wieku matki w chwili porodu. Wartości zaznaczone czcionką pogrubioną są istotne statystyczne na poz. α = 0, < 271 < < < < < < < > 289 < > < than 20 have smaller body dimensions than those delivered by older mothers. Uterine flexibility is, in this case, a global notion; it combines genetic, physiological (taking into account hormonal and mother fetus transport factors), and anatomical factors (placenta mass, villous surface, and umbil ical cord length) [8]. Interpreting the present results one can say that mothers years old are in the optimal age for delivering well developed children. For mothers over 30 years old, a lowering of neonatal wellness was discovered, probably caused by the beginnings of development stagnation. This leads to almost invisible anatomic physical changes which, following the authors cited above, can be described as physiological uterus capacity. The authors concluded that the mother s age during pregnancy and delivery has a significant influence on the newborn s wellness. Newborns delivered by teenage mothers have the lowest well ness level. The lower wellness level causes decreased body weight and length. The head and chest circumferences are less affected by the low wellness level. The optimal maternal age for deliv ering a well developed newborn is years. Teenage mothers in whom the development process is not completed deliver newborns with smaller body dimensions than older mothers. For mothers over 30 years old, decreased wellness in the perina tal period was discovered. This is caused by the beginnings of the development stagnation.

5 Maternal Age and Neonatal Development 653 Table 3. Variability of neonatal head circumference according to the newborn s and mother s ages at delivery. Values which are significantly different are in bold Tabela 3. Zróżnicowanie obwodu głowy noworodków z uwzględnieniem ich wieku, płci oraz wieku matki w chwili porodu. Wartości zaznaczone czcionką pogrubioną są istotne statystyczne na poziomie α = 0, < 271 < < < < < < < > 289 < > < References [1] Piasecki E: Charakterystyka populacyjna ciężaru ciała noworodków polskich. MiPA 1988, 109, [2] Abdul Karim RW, Beydoun SN: Growth of the human fetus. Clin Obstet Gynecol 1974, 17, [3] Miller JE: Determinants of intrauterine growth retardation: evidence against maternal depletion. J Biosoc Sci 1989, 21, [4] Bożiłow W, Sawicki K, Poradnik E, Kurlej W, Gworys B: Zmienność masy ciała podczas rozwoju prenatalnego i okołoporodowego. Przegl Antrop 1992, 55, 1 2, [5] Cieślik K, Waszak M: Z badań nad wpływem czynników pozagenetycznych na rozwój płodu oraz ich udziału w przyczynach urodzeń martwych. Przegl Antrop 1988, 54, [6] Orkwiszewska A, Gładykowska Rzeczycka J: Częstość urodzeń i stan rozwoju noworodków przedwcześnie urodzonych z wagą ciała poniżej 2500 g w rejonie Gdańska. Przegl Antrop 1994, 57, [7] Thompson AM, Billewicz WZ, Hytten FE: The assessment of fetal growth. J Obstet Gynaecol Br Cmwlth 1968, 75, [8] Gworys B, Kordecki H: The neonate wellness dependency on the level of mother fetus transport development. In press. Pol J Environmental Stud 2008.

6 654 B. GWORYS et al. Table 4. Variability of neonatal chest circumference according to the newborn s and mother s ages at delivery. No statisti cally significant differences were discovered Tabela 4. Zróżnicowanie obwodu klatki piersiowej noworodków z uwzględnieniem ich wieku, płci oraz wieku matki w chwili porodu. Nie stwierdzono istotnych statystycznie różnic < 271 < < < < < < < > 289 < > < Address for correspondence: Bohdan Gworys Department of Normal Anatomy Silesian Piasts University of Medicine Chałubińskiego 6a Wrocław Poland Tel.: E mail: bgworys@gmail.com Conflict of interest: None declared Received: Revised: Accepted: