ORIGINAL PAPERS Adv Clin Exp Med 2008, 17, 6, 649 654 ISSN 1230 025X 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, 649 654). 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, 649 654). 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
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 1989 2001 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, 272 280, 281 288, 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 = 0.05. 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.
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 = 0,05 10 503 26.3 421 591 < 271 < 20 13 507 24.2 430 602 < 271 32 521 22.5 432 587 20 23 31 531 25.3 421 589 29 523 24.1 385 599 24 27 26 528 26.4 458 652 18 513 26.7 421 579 28 31 22 509 25.9 439 677 12 514 25.11 462 612 32 35 14 512 23.9 429 578 11 509 23.17 483 592 < 35 10 511 25.7 471 579 29 514 25.1 485 633 272 280 < 20 31 517 26.7 429 645 272 280 58 543 21.8 458 673 20 23 72 554 25.8 4 3 658 66 537 22.1 471 658 24 27 66 553 27.3 473 599 28 523 25.8 399 587 28 31 41 531 26.3 418 703 21 521 27.5 432 605 32 35 30 526 25.9 467 607 22 517 26.2 493 669 < 35 23 526 24.7 431 634 31 516 24.9 461 599 281 288 < 20 27 519 27.2 407 579 281 288 69 545 21.6 469 703 20 23 69 551 25.3 453 673 61 541 23.1 487 689 24 27 65 554 24.8 466 639 34 536 22.8 483 742 28 31 32 549 26.0 419 680 25 531 24.6 457 688 32 35 28 532 25.1 432 679 21 519 26.2 462 657 < 35 19 522 27.4 466 688 17 514 25.9 472 645 > 289 < 20 16 521 26.4 483 672 > 289 46 545 24.5 488 638 20 23 42 547 25.7 468 688 41 541 23.8 442 678 24 27 37 543 27.9 461 632 27 537 24.6 462 598 28 31 19 531 26.4 387 622 18 526 26.2 468 689 32 35 14 519 27.4 451 627 16 519 28.3 465 677 < 35 11 521 24.9 439 672 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
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 = 0,05 10 2900 449 1800 4520 < 271 < 20 13 2850 530 1320 4330 < 271 32 3202 432 1250 4310 20 23 31 3250 472 1820 4580 29 3221 504 1680 5030 24 27 26 3104 431 2030 4900 18 3180 502 2010 4590 28 31 22 3220 429 2000 5270 12 3289 471 1920 5100 32 35 14 3245 398 2190 5600 11 3209 399 1450 4300 < 35 10 3261 453 1570 5880 29 3129 429 2000 5400 272 280 < 20 31 3020 489 2000 5640 272 280 58 3430 409 2100 5620 20 23 72 3483 453 2100 5720 66 3388 387 2300 6720 24 27 66 3457 473 1980 6020 28 3202 471 2240 5840 28 31 41 3348 407 2310 5880 21 3287 433 2370 5990 32 35 30 3276 533 2100 5670 22 3292 494 2100 5670 < 35 23 3342 489 2210 5540 31 3199 502 2100 5320 281 288 < 20 27 3043 327 2000 5490 281 288 69 3453 471 2320 6000 20 23 69 3387 386 2310 5720 61 3388 442 2120 5430 24 27 65 3468 346 2100 5990 34 3326 462 2220 5780 28 31 32 3351 428 1840 5730 25 3402 419 2450 5470 32 35 28 3388 501 1990 5690 21 3377 439 2100 6020 < 35 19 3421 469 2010 5470 17 3284 488 2210 5890 > 289 < 20 16 3189 455 2200 5790 > 289 46 3507 513 2320 5600 20 23 42 3476 503 2320 5800 41 3542 471 2210 5460 24 27 37 3482 484 2310 5650 27 3488 434 2190 5820 28 31 19 3469 433 1790 6010 18 3505 451 2390 5440 32 35 14 3590 389 2000 5890 16 3592 473 2190 5880 < 35 11 3621 402 2100 6100 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 20 30 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 20 27 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.
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 = 0,05 10 321 19.2 234 489 < 271 < 20 13 318 18.7 210 521 < 271 32 329 18.7 219 467 20 23 31 327 18.6 231 489 29 327 18.6 254 509 24 27 26 329 21.2 233 523 18 329 16.9 318 541 28 31 22 326 18.8 213 459 12 326 17.9 252 478 32 35 14 327 19.4 241 529 11 329 18.1 234 469 < 35 10 329 20.1 233 478 29 322 21.3 217 511 272 280 < 20 31 324 22.1 239 533 272 280 58 334 18.7 287 465 20 23 72 338 19.8 221 430 66 332 19.3 231 509 24 27 66 336 18.6 294 523 28 333 18.2 246 576 28 31 41 341 19.5 258 511 21 337 19.7 211 41 32 35 30 334 19.2 238 479 22 335 20.2 238 479 < 35 23 335 20.3 237 543 31 324 20.4 216 499 281 288 < 20 27 329 21.8 219 499 281 288 69 343 18.9 251 532 20 23 69 342 18.5 232 476 61 347 17.8 264 479 24 27 65 339 17.8 241 569 34 345 17.9 232 513 28 31 32 343 19.3 214 478 25 339 19.3 241 469 32 35 28 348 18.6 241 553 21 343 17.5 228 518 < 35 19 347 20.4 238 463 17 326 21.1 217 499 > 289 < 20 16 328 22.0 229 562 > 289 46 337 19.2 238 470 20 23 42 339 20.1 267 510 41 337 19.6 215 543 24 27 37 338 18.9 251 499 27 341 17.8 237 531 28 31 19 352 18.9 237 531 18 339 18.2 251 488 32 35 14 343 17.3 231 469 16 335 17.9 216 469 < 35 11 337 19.9 263 405 References [1] Piasecki E: Charakterystyka populacyjna ciężaru ciała noworodków polskich. MiPA 1988, 109, 159 196. [2] Abdul Karim RW, Beydoun SN: Growth of the human fetus. Clin Obstet Gynecol 1974, 17, 37 52. [3] Miller JE: Determinants of intrauterine growth retardation: evidence against maternal depletion. J Biosoc Sci 1989, 21, 235 243. [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, 45 55. [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, 151 158. [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, 33 37. [7] Thompson AM, Billewicz WZ, Hytten FE: The assessment of fetal growth. J Obstet Gynaecol Br Cmwlth 1968, 75, 903 916. [8] Gworys B, Kordecki H: The neonate wellness dependency on the level of mother fetus transport development. In press. Pol J Environmental Stud 2008.
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 10 317 14.3 212 501 < 271 < 20 13 314 23.8 245 487 < 271 32 319 15.6 234 478 20 23 31 317 24.9 221 488 29 321 24.9 231 478 24 27 26 318 15.3 233 495 18 318 27.8 212 503 28 31 22 321 25.3 225 506 12 321 21.0 217 462 32 35 14 318 21.2 211 489 11 318 17.6 243 468 < 35 10 319 20.2 241 467 29 328 21.8 232 498 272 280 < 20 31 331 19.8 229 502 272 280 58 329 17.8 241 506 20 23 72 331 17.2 232 488 66 327 16.3 241 482 24 27 66 328 18.3 241 499 28 329 17.8 226 477 28 31 41 326 15.3 219 488 21 332 18.2 225 495 32 35 30 337 16.9 229 469 22 328 14.8 231 512 < 35 23 329 16.2 251 479 31 331 20.2 269 492 281 288 < 20 27 328 19.0 278 416 281 288 69 335 16.7 245 511 20 23 69 331 18.4 264 463 61 334 16.3 235 521 24 27 65 334 18.6 253 503 34 334 18.9 230 465 28 31 32 329 19.2 239 465 25 335 20.3 246 521 32 35 28 331 18.6 222 498 21 336 20.3 228 459 < 35 19 329 19.3 251 507 17 332 16.9 212 476 > 289 < 20 16 328 17.6 231 462 > 289 46 336 17.3 243 439 20 23 42 328 16.9 251 478 41 334 15.7 261 520 24 27 37 332 12.9 230 460 27 337 16.1 216 492 28 31 19 336 17.9 228 476 18 334 14.8 225 471 32 35 14 337 16.3 219 483 16 337 18.3 231 494 < 35 11 334 19.9 248 506 Address for correspondence: Bohdan Gworys Department of Normal Anatomy Silesian Piasts University of Medicine Chałubińskiego 6a 50 368 Wrocław Poland Tel.: +48 71 784 13 42 E mail: bgworys@gmail.com Conflict of interest: None declared Received: 7.10.2008 Revised: 10.11.2008 Accepted: 21.11.200