Hypergonadotrophinaemia with reduced uterine and ovarian size in women born small-for-gestational-age

Lourdes Ibáñez1,6, Neus Potau2, Goya Enriquez3, Maria Victoria Marcos4 and Francis de Zegher5

1 Endocrinology Unit, Hospital Sant Joan de Déu, University of Barcelona, 2 Hormonal Laboratory and 3 Department of Radiology, Hospital Materno-Infantil Vall d’Hebron, Autonomous University of Barcelona, 4 Endocrinology Unit, Hospital de Terrassa, Terrassa, Spain and 5 Department of Pediatrics, University of Leuven, Belgium

6 To whom correspondence should be addressed at: Endocrinology Unit, Hospital Sant Joan de Déu, University of Barcelona, Passeig de Sant Joan de Déu, 2, 08950 Esplugues, Barcelona, Spain. e-mail: libanez{at}hsjdbcn.org


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
BACKGROUND: Fetal growth restraint has been associated with FSH hypersecretion in early infancy and in early post-menarche, and with reduced uterine and ovarian size in adolescence. It is unknown whether these reproductive anomalies persist, respectively, into late infancy and into the reproductive age range. METHODS: We report follow-up findings in two age groups of girls. A cohort of infants [n = 26; n = 10 born appropriate-for-gestational-age (AGA) and n = 16 born small-for-gestational-age (SGA)], who had been studied at the age of ~4 months, was assessed again at the age of 12 months. A cohort of teenagers (n = 28), who had been studied at the age of ~14 years, was assessed again at the age of ~18 years; this group was complemented by a transversal cohort of similar age (n = 19) for a total of 47 young women (n = 27 AGA; n = 20 SGA). In infants, only serum FSH was measured; adolescents underwent endocrine-metabolic screening, ultrasound assessment of uterine-ovarian size, and evaluation of body composition by dual X-ray absorptiometry. RESULTS: Serum FSH levels were higher in SGA than AGA infant girls at 4 and 12 months, and higher in SGA than AGA adolescents at 14 and 18 years (all P < 0.01). Longitudinal ultrasound assessments disclosed a late-adolescent increment of uterine size that was less obvious in SGA than AGA girls. In contrast, ovarian volume remained stable in both subgroups. Compilation of longitudinal and transversal results at 18 years of age corroborated the persistent reduction in the uterine size of SGA girls (by ~20%; P < 0.005) and in their ovarian volume (by ~40%; P < 0.0001); moreover, SGA girls displayed not only a persistent elevation of FSH (by ~50%; P < 0.001), but also a rise of LH and fasting insulin, as well as an excess of abdominal fat (all P < 0.01). CONCLUSIONS: The gynaecology of young women born SGA was found to be characterized by hypergonadotrophinaemia and by a reduced uterine and ovarian size.

Key words: FSH/LH/ovary/small-for-gestational-age/uterus


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Prenatal life is a critical window in the development of the female internal genitalia (Macklon and Fauser, 1999Go). Fetal growth restraint has been associated with FSH hypersecretion in early infancy and in early post-menarche, and with reduced uterine and ovarian size in adolescence (Ibáñez et al., 1999,Go 2000a, 2002a). However, it is unknown whether these reproductive anomalies persist, respectively, until late infancy and into adulthood. Here, we report longitudinal observations indicating that the reproductive anomalies in girls born small-for-gestational-age (SGA) are indeed persistent, and may even be amplified into the reproductive age range.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Study population
We report follow-up findings in two age groups of girls: infants and teenagers.

The infant population (n = 26), who had been studied at the age of ~4 months (Ibáñez et al., 2002aGo), was assessed again at the age of 12 months. The original study cohort was recruited at Barcelona Hospital and was composed of infant girls (postnatal age range, 3–6 months) in good general condition. Blood was sampled from this cohort, independently of this study and of birthweight, for either follow-up or screening purposes, before elective minor surgery, or after recovery of intercurrent viral illness. Inclusion criteria were weight at term birth (37–41 weeks) either appropriate for gestational age (AGA, birthweight between –1 and +1 SD, n = 10), or small for gestational age (SGA, birthweight <2.5 SD, n = 16). Exclusion criteria were: evidence for a syndromatic, chromosomal, or infectious aetiology of low birthweight; hypothyroidism; urogenital tract abnormalities; systemic disease or acute illness; and persistent growth failure (Ibáñez et al., 2002aGo).

The teenage population (n = 36), who had been studied at the age of ~14 years of age (Ibáñez et al., 2000aGo), was assessed again at the age of ~18 years, with the exception of eight girls, who were either on oral contraceptives (n = 6) or pregnant (n = 1), or could not be located (n = 1). Of the remaining 28 subjects, 18 were born AGA and 10 SGA.

To evaluate reproductive indices at the age of 18 years in a larger group, the longitudinal cohort was complemented by a cross-sectional cohort (mean age, 17.8 years; n = 19); of those, nine were born AGA and 10 SGA. These girls were recruited among healthy relatives of hospital staff (n = 31), and among asymptomatic girls attending the endocrine clinic for evaluation of thyroid function (n = 1), pubertal development (n = 5), or post-menarcheal growth status (n = 10). In the latter girls, we documented, respectively, euthyroidism, normal variation in timing of puberty, and post-menarcheal stature above/within (n = 7) or below (n = 3) target height range. The exclusion criteria were: evidence for a syndromatic, chromosomal, or infectious aetiology of low birthweight; thyroid dysfunction; Cushing syndrome; hyperprolactinaemia; previous or current use of oral contraceptive medication; and a family or personal history of diabetes mellitus (criteria of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 1997).

Birthweight and gestational age data were obtained from hospital records or from the girls’ paediatricians, and transformed into SD scores (Ibáñez et al., 1998Go).

Study design
In the infant population, serum FSH was measured at 12 months, and the values were interpreted in view of those obtained at 4 months.

In the late-adolescent or young-adult population, body composition assessment and pelvic ultrasound examinations were performed together with blood sampling for measurement of serum glucose, insulin, LH, FSH, estradiol, testosterone, and sex hormone-binding globulin (SHBG). Ultrasound examinations and endocrine-metabolic measurements were performed in the follicular phase (range: day 5 ± 3) of the menstrual cycle.

Ultrasonography
The ultrasound examinations were performed in a full-bladder state. Scans were obtained by a single observer (G.E.) using an Acuson Sequoia 512 (Mountain View, CA, USA) with a 4–6 MHz multifrequency sector probe. Throughout the study, the observer remained blinded to the girls’ birthweight.

Longitudinal and transverse views of the uterus were obtained and measurements made of uterine length (from the top of the fundus to the cervix), anteroposterior diameters of the fundus and cervix, and uterine cross-sectional area (uterine length x uterine anteroposterior diameter).

Longitudinal and transverse views of the ovaries were obtained for measurement of length, breadth and depth of each ovary. Ovarian volume (right and left) was calculated using the formula for a modified prolate ellipsoid (depth x breadth x length/2) (Griffin et al., 1995Go; Buzzi et al., 1998Go; Ibáñez et al., 2000aGo). For comparisons between AGA and SGA groups, average volumes of right and left ovary of each girl were used.

Body composition
Body composition was assessed by dual-energy X-ray absorptiometry (DXA) using a Lunar Prodigy machine. All studies were performed using Lunar software programs (versions 3.4 and 3.5, Lunar Corp., Madison, USA) (Ibáñez et al., 2000bGo). Absolute fat and lean mass (kg) were assessed for the whole body, and also by specific body regions. The truncal region was defined as the tissue area bordered by a horizontal line below the chin, vertical borders lateral to the ribs, and oblique lines passing through the femoral necks. The abdominal region was defined as the area encompassed between the dome of the diaphragm (cephalad limit) and the top of the greater throcanter (caudal limit) (Taylor et al., 1998Go). The total radiation dose in each examination was 0.1 mSv. The coefficients of variation (CV) for scanning precision, calculated from 30 consecutive scans of an external hydroxyapatite, luciate and high-density polyethylene Hologic phantom (Hologic Inc., Waltham, MA, USA), were 2.0 and 2.6% respectively for fat and lean body mass (Kiebzak et al., 2000Go). The intra-individual CV for abdominal fat mass was 0.7%, as assessed by three consecutive scans of 14 persons.

Endocrinology
Serum glucose was assessed by the glucose oxidase method. Serum LH, FSH, SHBG and insulin were measured by immuno-chemiluminiscence (IMMULITE 2000, Diagnostic Products Corp, Los Angeles, CA, USA), the intra-and inter-assay CVs were 6.2 and 7.0% for LH, 4.3 and 6.3% for FSH, 4.2 and and 6.6% for SHBG, and 4.4 and 8.6% for insulin. Serum estradiol was determined by third generation RIA (DSL, Webster, Texas, USA), with a detection limit of 0.6 pg/ml; the intra- and inter-assay CVs were 3.5 and 4.9% respectively; serum testosterone was assessed by RIA, as described previously (Ibáñez et al., 2001aGo).

Statistics and Ethics
Results are expressed as mean ± SEM, unless stated otherwise. Two-sided t-test was used for statistical comparisons; significance level was set at P < 0.05.

The study protocol was approved by the Institutional Review Board of the Barcelona Hospital. Informed consent was obtained from the parents and/or the girls.


    Results
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 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
The longitudinal findings in infants and adolescents are summarized in Figures 1 and 2, and in Table I; the compiled results obtained at age ~18 years are listed in Table II.



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Figure 1. Serum FSH concentrations in appropriate-for-gestational age (AGA) versus small-for-gestational age (SGA) infant and adolescent girls. At all studied ages, serum FSH was higher in SGA than in AGA girls (all P < 0.01).

 


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Figure 2. Changes in uterine length and mean ovarian volume between 14 and 18 years in appropriate-for-gestational age (AGA) versus small-for-gestational age (SGA) girls.

 

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Table I. Longitudinal clinical, biochemical and ultrasonographic indices in adolescents and young women born either appropriate for gestational age (AGA) or small for gestational age (SGA). Weight at term birth was 3.3 kg for AGA and 2.1 kg for SGA subgroups, their respective age at menarche being 12.5 and 12.2 years
 

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Table II. Clinical and endocrine-metabolic variables, ultrasonographic parameters, and indices of body composition in young women born either appropriate for gestational age (AGA) or small for gestational age (SGA)
 
Serum FSH levels were higher in SGA than in AGA infant girls at 4 and 12 months (each P < 0.01); post-menarche, FSH was still higher in SGA than in AGA adolescents at ~14 and at ~18 years of age. Both in the infant and in the teenage phase, the difference in FSH between AGA and SGA cohorts was more pronounced in older than in younger girls (Figure 1 and Table I).

Longitudinal ultrasound assessments disclosed a late-adolescent increment of uterine size. This increment was less obvious in SGA than AGA girls, possibly as a reflection of the differences already apparent at ~14 years; consequently, these differences in uterine size were amplified, rather than attenuated, by ~18 years of age. In contrast, ovarian volume remained stable in both AGA and SGA girls (Figure 2); this observation implies that the striking difference of ovarian size between AGA and SGA adolescents persists into adulthood (Table I).

The compiled longitudinal and cross-sectional results at ~18 years corroborated the persistent reduction in the uterine size of SGA girls (mean difference ~20%; P < 0.005) and in their ovarian volume (mean difference ~40%; P < 0.0001); moreover, SGA girls displayed a persistent elevation of FSH (by ~50%; P < 0.001) and a raised LH and fasting insulin, as well as an excess of abdominal fat (all P < 0.01; Figure 3 and Table II).



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Figure 3. Serum LH and FSH concentrations, uterine area and mean ovarian volume at 18 years of age in appropriate-for-gestational age (AGA) versus small-for-gestational age (SGA) girls. Means are indicated by squares, standard deviation by whiskers and SEM by rectangles.

 
The differences in uterine and ovarian size between AGA and SGA girls remained similar and significant after matching AGA and SGA subpopulations for height, weight and BMI, suggesting that the reduced size of the internal genitalia in SGA girls is essentially independent of the reduction in their total body size.


    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
The human gonadotrophic axis is characterized by two postnatal phases of high activity, one in infancy and another starting in puberty and persisting into adulthood. In girls, prenatal growth restraint is known to be followed by changes in the gonadotrophic axis (elevated FSH, normal inhibin B) and in the size of the internal genitalia (small uterus and ovaries) both at a young age within the infantile phase (at 3–6 months) and/or the adolescent phase (at 14 years) (Ibáñez et al., 2000aGo, 2000c, 2002a).

The present longitudinal findings were obtained at older ages within these phases (at 12 months and 18 years), and they indicate that the SGA-related alterations persist over time, not only into late infancy, but also into the reproductive age range.

The infant and adolescent girls participating in this study were selected according to birthweight for gestational age. Besides gonadotrophin and gynaecological ultrasound abnormalities, the SGA adolescents in this cohort also presented hyperinsulinaemia, abdominal fat excess, a reduced lean body mass, and subclinical hyperandrogenism, as previously reported in adolescent SGA girls who had been selected through similar (Barker et al., 1997Go; Ibáñez et al., 1999,Go 2002b) or other criteria, e.g. precocious pubarche (Ibáñez et al., 1998Go; 2001b, 2003), anovulation (Ibáñez et al., 2002dGo), early puberty and/or short stature (Chiarelli et al., 1999Go; Ibáñez et al., 2000dGo).

The LH increase at 18 years in the SGA population can be a sign of incipient polycystic ovary syndrome (PCOS); in fact, autonomous hypothalamic GnRH signalling resulting in disorderly LH secretion has been described in PCOS adolescents (Veldhuis et al., 2001Go). The relatively unrestrained LH production may be partly driven by hyperinsulinemia.

The longitudinal data obtained between 14 and 18 years of age evidenced that the uterus tends to grow further in late adolescence, whereas this is not the case for the ovaries; the AGA-versus-SGA differences for FSH and for uterine-ovarian size remained stable or were slightly amplified over this timespan. Hence, any SGA-related anomalies of these endocrine-ultrasound indices in young women seem to be largely predictable by early post-menarche; conversely, normal results in early post-menarche may be viewed as reassuring with respect to reproductive potential, although SGA-related anovulation or oligo-ovulation may still occur (Ibáñez et al., 2002cGo).

The early detection of SGA-related anomalies in reproductive organs and body composition is a perspective of mounting relevance, as it starts to have therapeutic consequences. For example, SGA-related central adiposity with anovulation or oligo-ovulation responds well, in teenage girls, to therapy with metformin (Ibáñez et al., 2002dGo). It remains to be studied, however, whether metformin treatment also has the capacity to modify uterine-ovarian size in SGA girls, and to attenuate any potential inter-generational effects of reduced uterine size. Indeed, birthweight of the mother is the prime factor accounting for the variability in the birthweight of human infants (Ounsted and Ounsted, 1968Go; Klebanoff et al., 1989Go; Hennessy et al., 1998Go), and women born SGA are at risk for delivering, in turn, SGA and preterm infants (Klebanoff et al., 1989Go; Magnus et al., 1997Go; Hennessy et al., 1998Go). Conceivably, a non-genomic mechanism, that modulates uterine size prenatally, provides a survival advantage, as it would allow the adaption of fetal growth in each generation, according to the growth conditions that the mother herself experienced as a fetus.

In conclusion, the gynaecology of young women born SGA was found to be characterized by persisting hypergonadotrophinaemia and by a reduced uterine and ovarian size; this is one more example of a gynaecological entity with an obstetric history. That the link between this entity and fetal restraint has escaped attention for so long, may in part be attributable to the fact that the majority of SGA women do not have a strikingly short stature, and therefore do not present an obvious reminder of their prenatal growth restraint.


    Acknowledgements
 
We thank Luis del Río, MD, and Joaquin Rosales for performing body composition assessments and Maria Jesús Gras for hormone measurements. The study was supported by a Visiting Fellowship from the European Society for Pediatric Endocrinology. FdZ is a Clinical Research Investigator of the Fund for Scientific Research, Flanders, Belgium.


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Barker, M., Robinson S., Osmond, C. and Barker, D.J.P. (1997) Birth weight and body fat distribution in adolescent girls. Arch. Dis. Child., 77, 381–383.[Abstract/Free Full Text]

Buzzi, F., Pilotta, A., Dordoni, D., Lombardi, A., Zaglio, S. and Adlard, P. (1998) Pelvic ultrasonography in normal girls and in girls with pubertal precocity. Acta Paediatr. Scand., 87, 1138–1145.

Chiarelli, F., di Ricco, L., Mohn, A., De Martino, M. and Verrotti, A. (1999) Insulin resistance in short children with intrauterine growth retardation. Acta Paediatr. Scand., (Suppl. 88), 428, 62–65.

Griffin, I.J., Cole, T.J., Duncan, K.A., Hollman, A.S. and Donaldson, M.D.C. (1995) Pelvic ultrasound measurements in normal girls. Acta Paediatr. Scand., 84, 536–543.

Hennessy, E. and Alberman, E. (1998) Intergenerational influences affecting birth outcome. I. Birthweight for gestational age in the children of the 1958 British birth cohort. Paediatr. Perinat. Epidemiol., (Suppl. 1), 12, 45–60.[CrossRef][ISI][Medline]

Ibáñez, L., Potau, N., Francois, I. and de Zegher, F. (1998) Precocious pubarche, hyperinsulinism and ovarian hyperandrogenism in girls: relation to reduced fetal growth. J. Clin. Endocrinol. Metab., 83, 3558–3662.[Abstract/Free Full Text]

Ibáñez, L., Potau, N., Marcos, M.V. and de Zegher, F. (1999) Exaggerated adrenarche and hyperinsulinism in adolescent girls born small for gestational age. J. Clin. Endocrinol. Metab. 84, 4739–4741.[Abstract/Free Full Text]

Ibáñez, L., Potau, N., Enríquez, G. and de Zegher, F. (2000a) Reduced uterine and ovarian size in adolescent girls born small for gestational age. Pediatr. Res., 47, 575–577.[Abstract/Free Full Text]

Ibáñez, L., Potau, N., Ong, K., Dunger, D.B. and de Zegher, F. (2000b) Increased bone mineral density and serum leptin in non-obese girls with precocious pubarche: relation to low birthweight and hyperinsulinism. Horm. Res., 54, 192–197.[CrossRef][ISI][Medline]

Ibáñez, L., Potau, N. and de Zegher, F. (2000c) Ovarian hyporesponsiveness to follicle stimulating hormone in adolescent girls born small for gestational age. J. Clin. Endocrinol. Metab., 85, 2624–2626.[Abstract/Free Full Text]

Ibáñez, L., Ferrer, A., Marcos, M.V., Rodriguez-Hierro, F. and de Zegher, F. (2000d) Early puberty: rapid progression and reduced final height in girls with low birthweight. Pediatrics, 106, 72.[CrossRef]

Ibáñez, L., Valls, C., Ferrer, A., Marcos, M.V., Rodriguez-Hierro, F. and de Zegher, F. (2001a) Sensitization to insulin induces ovulation in non-obese adolescents with anovulatory hyperandrogenism. J. Clin. Endocrinol. Metab., 86, 3595–3598.[Abstract/Free Full Text]

Ibáñez, L., Valls, C., Potau, N., Marcos, M.V. and de Zegher, F. (2001b) Polycystic ovary syndrome after precocious pubarche: Ontogeny of the low-birthweight effect. Clin. Endocrinol., 55, 667–672.[CrossRef][ISI][Medline]

Ibáñez, L., Valls, C., Cols, M., Ferrer, A., Marcos, M.V. and de Zegher, F. (2002a) Hypersecretion of follicle stimulating hormone in infant boys and girls born small for gestational age. J. Clin. Endocrinol. Metab., 87, 1986–1988.[Abstract/Free Full Text]

Ibáñez, L., Valls, C., Miró, E., Marcos, M.V. and de Zegher, F. (2002b) Early menarche and subclinical ovarian hyperandrogenism in girls with reduced adult height after low birthweight. J. Pediatr. Endocrinol. Metab., 15, 431–433.[ISI][Medline]

Ibáñez, L., Potau, N., Ferrer, A., Rodriguez-Hierro, F., Marcos, M.V. and de Zegher, F. (2002c) Reduced ovulation rate in adolescent girls born small for gestational age. J. Clin. Endocrinol. Metab., 87, 3391–3393.[Abstract/Free Full Text]

Ibáñez, L., Potau, N., Ferrer, A., Rodriguez-Hierro, F., Marcos, M.V. and de Zegher, F. (2002d) Anovulation in eumenorrheic, non-obese adolescent girls born small for gestational age: insulin sensitization induces ovulation, increases lean body mass, and reduces abdominal fat excess, dyslipidemia and subclinical hyperandrogenism. J. Clin. Endocrinol. Metab., 87, 5702–5705.[Abstract/Free Full Text]

Ibáñez, L., Ong, K., de Zegher, F., Marcos, M.V., del Rio, L. and Dunger, D. (2003) Fat distribution in non-obese girls with and without precocious pubarche: central adiposity related to insulinemia and androgenemia from pre-puberty to post-menarche. Clin. Endocrinol., 58, 372–379.[CrossRef][ISI][Medline]

Kiebzak, G.M., Leamy, L.J., Pierson, L.M., Nord, R.H. and Zhang, Z.Y. (2000) Measurement precission of body composition variables using the Lunar DPX-L densitometer. J. Clin. Densitometry, 3, 35–41.[ISI][Medline]

Klebanoff, M.A., Meirik, O. and Berendes, H.W. (1989) Second-generation consequences of small-for-dates birth. Pediatrics, 84, 343–347.[Abstract]

Macklon, N.S. and Fauser, B.C.J.M. (1999) Aspects of ovarian follicle development throughout life. Horm. Res., 52, 161–170.[CrossRef]

Magnus, P., Bakketeig, L.S. and Hoffman, H. (1997) Birth weight of relatives by maternal tendency to repeat small-for gestational age (SGA) births in successive pregnancies. Acta Obstet. Gynecol. Scand., (Suppl. 165), 76, 35–38.[ISI]

Ounsted, M. and Ounsted, C. (1968) Rate of intrauterine growth. Nature, 220, 599–600.[ISI][Medline]

Taylor, R.W., Keil, D., Gold, E.J., Williams, S.M. and Goulding, A. (1998) Body mass index, waist girth, and waist-to-hip ratio as indexes of total and regional adiposity in women: evaluation using receiver operating characteristic curves. Am. J. Clin. Nutr., 67, 44–49.[Abstract]

The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. (1997) Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care, 20, 1183–1197.[ISI][Medline]

Veldhuis, J.D., Pincus, S.M., Garcia-Rudaz, M.C., Ropelato, M.G., Escobar, M.E. and Barontini, M. (2001) Disruption of the joint synchrony of luteinizing hormone, testosterone, and androstenedione secretion in adolescents with polycystic ovarian syndrome. J. Clin. Endocrinol. Metab., 86, 72–79.[Abstract/Free Full Text]

Submitted on April 2, 2003; accepted on May 8, 2003.