Perinatal outcomes in dichorionic diamniotic twins with multifetal pregnancy reduction versus expectant management: A systematic review and meta-analysis.

BACKGROUND: Published findings on perinatal outcomes of multifetal pregnancy reduction (MPR) of dichorionic diamniotic (DCDA) twin pregnancy to singleton are controversial. We performed a meta-analysis to appraise the effects of MPR of DCDA twin pregnancy versus expectant management on perinatal outcomes. METHODS: Four electronic databases were searched from their inception to June 15, 2019, to identify publications that appraised MPR before 15 weeks of gestation. Studies reporting perinatal outcomes of both MPR of DCDA twin pregnancy to singleton and expectant management were considered. The relative risks (RRs) and mean differences with 95% confidence intervals (CIs) were pooled using a random-effects model. RESULTS: Six studies involving 7398 participants showed that MPR of DCDA twin pregnancy to singleton was associated with a lower risk of preterm birth (5 studies with 7297 participants; RR: 0.30, 95% CI: 0.22-0.40; P < .001) and higher birth weight (4 studies with 5763 participants; mean differences: 548.10 g, 95% CI: 424.04-672.15; P < .001) than expectant management; there was no difference in the occurrence of miscarriages (5 studies with 7355 participants; RR: 1.57, 95% CI: 0.90-2.75; P = .11). Sensitivity analysis showed that all the results were stable and reliable, with the omission of 2 studies with serious risk of bias. CONCLUSION: Compared to expectant management, MPR of DCDA twin pregnancy to singleton prevents preterm birth and low birth weight, without increasing the risk of miscarriages. Regarding perinatal morbidity related to preterm birth, MPR can be reserved as a remediation measure to improve the perinatal outcomes of DCDA twin pregnancies.

The Effect of Chorionicity on Maternal Cardiac Adaptation to Uncomplicated Twin Pregnancy: A Prospective Longitudinal Study.

OBJECTIVE: The objective of this study was to longitudinally evaluate maternal echocardiographic findings in uncomplicated twin gestations according to chorionicity. METHODS: Healthy women with twin pregnancy were assessed with transthoracic echocardiography across the first, second, and third trimesters. Cardiac findings were compared within each group and between monochorionic (MC) and dicho-rionic (DC) pregnancies. RESULTS: Overall, 19 MC and 48 DC uncomplicated twin pregnancies were included. In the MC group, no significant maternal haemodynamic changes were documented across gestation, with the exception of a decrease in ejection fraction. Compared to DC pregnancies, in the MC set lower cardiac output (second and third trimester, p = 0.001 and p = 0.006, respectively) and higher total vascular resistance (first trimester, p = 0.032) were observed. Regarding the diastolic function in MC twins, significantly higher values were observed for mitral E/A ratio (third trimester, p = 0.014), septal mitral E1/A1 ratio (third trimester, p = 0.030), lateral mitral E1 (second and third trimester, p = 0.014 and p = 0.029, respectively), and E1/A1 ratio (third trimester, p = 0.006). CONCLUSIONS: Maternal cardiac adaptation in twin pregnancy seems to differ significantly according to chorionicity. In particular, in MC pregnancies the impairment of diastolic function is less pronounced, presumably due to the lower circulating volume.

An integrative redescription of the nominal taxon for the Mesobiotus harmsworthi group (Tardigrada: Macrobiotidae) leads to descriptions of two new Mesobiotus species from Arctic.

The Mesobiotus harmsworthi group has a global distribution, with localities in polar, temperate and tropical zones. Since the first species of the harmsworthi group was described in the beginning of the 20th century, tens of new species within the group were found and named. However, the diagnosis of the nominal Mesobiotus harmsworthi is insufficient and enigmatic, thus it can be is a serious obstacle in solving the taxonomy of this group. Here, we integratively redescribe the nominal species for the genus Mesobiotus, i.e., Mesobiotus harmsworthi and clarify taxonomic statuses of the two subspecies: M. harmsworthi harmsworthi and M. harmsworthi obscurus that have been recognised as distinct taxa for more than three decades. Traditionally, egg chorion in M. harmsworthi was considered almost smooth and without any traces of areolation, however here we report many misunderstandings that accumulated across decades and we show that, in fact, the chorion in this species exhibits a partially developed areolation. We present an integrative (morphological, morphometric and molecular) diagnosis of the nominal taxon and we confirm that it differs from other species of the harmsworthi group by morphological characters of both animals and eggs. Additionally, we describe two new species of the genus Mesobiotus: M. skorackii sp. nov. from the Kyrgyz Republic (using classical morphological description) and M. occultatus sp. nov. from Svalbard Archipelago (by means of integrative taxonomy). Finally, we also provide the first genetic phylogeny of the genus Mesobiotus based on COI sequences which, together with molecular species delimitation, independently confirms the validity of the analysed taxa.

Comparison of three different fetometric formulas of ICC and BP for calculating the parturition date in a population of German Shepherd.

The aim of this study was to evaluate the suitability of three different formulas to predict the parturition date in German Shepherds, using the ultrasonographic fetometry method involving inner chorionic cavity diameter (ICC) and biparietal diameter (BP) measurements in the same population of a single breed. Overall, 53 ICC and 42 BP measurements were taken on 34 bitches. The measured values were substituted into breed-specific formulas for the German Shepherd as well as non-specific formulas for medium-sized bitches. Comparisons of clinical accuracy and statistical analyses of regression lines were performed to test the compatibility of the formulas used. We confirmed the similarity of our clinical results to outcomes obtained using the one breed-specific (Groppetti et al. 2015) and non-specific fetometry models (Luvoni and Grioni 2000), whereas another breed-specific formula (Milani et al. 2013) showed rather low accuracy. Comparing the clinical accuracy of the three formulas, the authors demonstrated that the Luvoni and Grioni (2000) formula for ICC dedicated to medium-sized dogs can also be effectively used in the German Shepherd, even with better results than breed-specific formulas by Groppetti et al. (2015). By contrast, the evaluation of BP formulas proves the successful usage of the Groppetti et al. (2015) formula to determine the date of birth by measuring scull bone structures (p < 0.05). The statistical analysis of regression lines were in agreement with the clinical results and confirmed the higher predictability of Groppetti et al. (2015) and Luvoni and Grioni (2000) formulas, than those of Milani et al. (2013).

Evaluation of Trichorionic versus Dichorionic Triplet Gestations from 2005 to 2016 in a Large, Referral Maternity Center.

Objective To evaluate trends in the proportions and outcomes of dichorionic-triamniotic (DT) compared with trichorionic-triamniotic (TT) triplet gestations. Methods This is a retrospective cohort of all triplet gestations identified by first trimester ultrasound at an academic center between 2005 and 2016. Primary outcomes were the change in proportion of DT versus TT triplets over time and the number of fetuses at delivery. Secondary outcomes included differences in mode of conception and maternal/perinatal outcomes by chorionicity. Results Of 258 identified triplet pregnancies, 65.5% (n = 169) were TT. The proportion of DT versus TT triplets increased from 2005 to 2016 (p < 0.001). Women with DT triplets were more likely to deliver a singleton (41.4 vs. 11.2%, p < 0.001). Mode of conception was known for 248 women, of whom 93.5% (n = 232) conceived through infertility treatment. Types of infertility treatment differed by chorionicity (p < 0.001), with DT triplets more likely to conceive through in vitro fertilization (88.3 vs. 60.7%). Women with DT delivered earlier than TT triplets (31.0 ± 5.0 vs. 33.1 ± 3.5 weeks; p = 0.03). Conclusion The proportion of DT triplet gestations increased significantly over time. Women with DT triplets delivered on average 2 weeks earlier than TT triplets. Women with DT triplets were more likely to reduce to a singleton gestation.

Prediction of whelping date in large and giant canine breeds by ultrasonography foetal biometry.

OBJECTIVES: To derive the growth curves of the inner chorionic cavity and the biparietal diameter in large and giant dog breeds by ultrasonographic foetal biometry. To evaluate their accuracy in the prediction of whelping date and the effect of litter size and foetal sex ratio. METHODS: Foetal biometry parameters were obtained using serial ultrasonographic examinations in eight large (26 to 40 kg) and nine giant (>40 kg) pregnant bitches with known breeding dates and concentrations of serum progesterone during oestrus. The relationship between inner chorionic cavity or biparietal diameter growth and days to parturition were analysed by linear regression and the equations derived from the growth curves were applied to predict the whelping day. The accuracy of the prediction (whelping day ±1 day and ±2 days) and the litter size and sex ratio were recorded. RESULTS: The results showed a significant relationship between days before parturition and inner chorionic cavity or biparietal diameter. The overall accuracy at ±2 days was greater, than that at ±1 day. In giant breed bitches, the accuracy of the prediction by biparietal diameter was significantly lower in small, than normal litter size. No effect of foetal sex ratio was observed. CLINICAL SIGNIFICANCE: Foetal biometry parameters obtained by ultrasonography can be used to predict whelping dates in large and giant dog breeds.

Neonatal outcomes of twin pregnancies delivered at late-preterm versus term gestation based on chorionicity and indication for delivery.

OBJECTIVE: To investigate the neonatal outcomes of twin pregnancies delivered at late-preterm versus term gestation based on chorionicity and indication for delivery. STUDY DESIGN: This is a retrospective cohort study of women with twin pregnancies delivered at ≥34 weeks of gestation from 1995 to 2014. Subjects were categorized into two groups according to gestational age at delivery: late-preterm group (34-36 weeks) and term group (≥37 weeks). Neonatal outcome measures including neonatal intensive care unit (NICU) admission, mechanical ventilator support, and respiratory distress syndrome (RDS) were compared between the late-preterm and term group based on chorionicity (monochorionic or dichorionic) and delivery indication (elective or non-elective). RESULTS: A total of 1198 twin pregnancies were included in the study: 679 in the late-preterm group and 519 in the term group. Late-preterm twin infants had higher rates of NICU admission, mechanical ventilator support, and RDS than did term twin infants, regardless of the chorionicity and indication for delivery. In the multivariable analysis, late-preterm birth, monochorionicity, and non-elective delivery were independently associated with a significantly higher risk of NICU admission and mechanical ventilator support. CONCLUSION: The late-preterm birth was associated with a higher risk of adverse neonatal outcome regardless of chorionicity and indication for delivery, and showed significantly increased risk by monochorionicity and non-elective delivery.

Optimal threshold for birth weight discordance: Does knowledge of chorionicity matter?

OBJECTIVE: To establish the optimal threshold of birth weight discordance (BWD) for prediction of stillbirth, perinatal mortality and morbidity in twins born in British Columbia with or without chorionicity information. STUDY DESIGN: This is a retrospective population-based cohort study of twins born in British Columbia from 2000 to 2010. Data from one hospital was used to adjust for chorionicity. Multivariate generalized estimating equation and receiver operating characteristic curve analyses were performed to evaluate the predictability of BWD in comparison with other fetal anthropometric measurements. Positive likelihood ratio is used to estimate test accuracy. Survival analysis was conducted to take gestational age and other confounders into account. RESULTS: We analyzed two cohorts, with (pairs=1493) and without (pairs=6328) chorionicity information, of which 1.5% experienced stillbirth, 2.9% suffered perinatal mortality and 22.6% identified with perinatal morbidities. BWD was a significant predictor of stillbirth. Standard receiver operating characteristic curve analysis and survival analysis suggested that BWD of ⩾30% is the optimal thresholds for stillbirth and perinatal mortality irrespective of chorionicity. However, the P-value for predictive accuracy of BWD was nonsignificant for perinatal morbidity, after adjusting for confounding variables engaging multivariate analysis. Sex discordance can be used as a proxy for chorionicity. CONCLUSION: BWD is a good predictor for stillbirth. A BWD cutoff limit of 30% and higher has optimal accuracy for detecting perinatal mortality.

Outcome of monochorionic-biamniotic twins conceived by assisted reproduction: a population-based study.

Objecive: To evaluate the perinatal outcome of monochorionic-diamniotic twins conceived by assisted reproduction technology (ART). METHODS: We compared data from a national population-based perinatal registry on perinatal outcomes of monochorionic-diamniotic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic-diamniotic twins. We compared maternal characteristics, pregnancy complications and perinatal outcomes. RESULTS: Monochorionic-diamniotic twin pregnancies (n=45) comprised 5.5% of all ART twins, and 9.3% of all monochorionic twins in this dataset. ART does not appear to increase the already high risk of monochorionicity compared to spontaneous conception, with the latter having an increased incidence for birth weight <1500 g [odds ratio (OD) 2.6, 95% confidence interval (CI) 1.2-5.4]. CONCLUSION: Our results disagree with hospital-based data and suggest that monochorionic-diamniotic twins following ART are not at increased risk of adverse perinatal outcomes compared to spontaneous monochorionic-diamniotic twins as well as to dichorionc twins conceived by ART.

Perinatal outcome of dichorionic-triamniotic as compared to trichorionic triplets.

OBJECTIVE: To evaluate if the perinatal outcomes of dichorionic-triamniotic (DC) triplets are significantly different than that of trichorionic (TC) triplets. STUDY DESIGN: Comparison of maternal and neonatal data of 44 DC to 46 TC triplets, using univariate analysis. RESULTS: DC triplets were significantly more common after spontaneous conception but all other maternal characteristics as well complications and cesarean section rates were similar. Both groups had similar incidence of birth at <32 and <28 weeks as well as similar incidence of very low and extremely low birth weight. There was similar incidence of neonatal morbidity except for twin-twin transfusion syndrome (13.6%) in the DC group. The stillbirth rate was 45/1000 and 29/1000, the early neonatal mortality rates were 63/1000 and 45/1000, and the perinatal mortality rate was 106/1000 and 72/1000 for DC and TC triplets, respectively (all not significantly different). CONCLUSIONS: Our data indicate that DC twins are not significantly disadvantaged compared to TC triplets and the similar outcomes might be reassuring for those who consider continuing their DC triplet pregnancy.

Ultrasonographic fetometry formulas of inner chorionic cavity diameter and biparietal diameter for medium-sized dogs can be used in giant breeds.

The aim of this study was to evaluate the suitability of the ultrasonographic fetometry method, involving inner chorionic cavity diameter (ICC) and biparietal diameter (BP) measurements, to predict the parturition date in giant breed dogs. Overall, 30 ICC and 24 BP measurements were taken on 24 giant breed bitches. The measured values were substituted into Luvoni and Grioni (2000) formulas for medium-sized bitches because formulas with ICC and BP to dogs with a body mass greater than 40 kg have not been defined. The accuracy of the parturition date predictions proved the method to be highly useful in the observed group of dogs. Prediction accuracy in the giants ranged between 54.16% (± 1 day, using BP) and 90% (± 2 days, using ICC), depending on the parameter measured and precision levels used. Numerically, the results obtained using ICC were better; however, no statistically significant differences between ICC and BP accuracy were found when comparing the effectiveness of the parturition date predictions. Regression lines based on the own fetometric measurements were highly convergent with the lines defined by Luvoni and Grioni (2000) formulas for medium-sized bitches. This outcome suggests a similar gestational development of fetuses in giant dogs and the possible use of Luvoni and Grioni (2000) formulas for medium-sized dogs with breeds weighing greater than 40 kg.

Reference charts for fetal biometric parameters in twin pregnancies according to chorionicity.

OBJECTIVE: The objective of this article is to determine reference values for fetal biometric parameters in twin pregnancies and to compare these values between monochorionic and dichorionic pregnancies. METHODS: A retrospective cross-sectional study was conducted among 157 monochorionic and 176 dichorionic twin pregnancies between 14 and 38 weeks of gestation. Biometric measurements included the biparietal diameter (BPD), abdominal circumference (AC), femurs length (FL) and estimated fetal weight (EFW). To evaluate the correlation between biometric parameters and gestational age, polynomial regression models were created, with adjustments using the coefficient of determination (R(2) ). Comparison between monochorionic and dichorionic pregnancies was performed using analysis of covariance. RESULTS: The mean BPD, AC, FL and EFW for the dichorionic pregnancies were 56.16 mm, 191.1 mm, 41.08 mm and 816.1 g, respectively. The mean BPD, AC, FL and EFW for the monochorionic pregnancies were 57.14 mm, 184.2 mm, 39.29 mm and 723.4 g, respectively. There was a statistical difference between mono and dichorionic pregnancies for all the biometric parameters (BPD p = 0.012; AC p = 0.047; FL p = 0.007; EFW p = 0.011). CONCLUSION: Reference curves of biometric parameters in twin pregnancies were determined. Biometric parameters were statistically different between monochorionic and dichorionic pregnancies.

Embryonic development of Zoraptera with special reference to external morphology, and its phylogenetic implications (Insecta).

The embryonic development of Zorotypus caudelli Karny (Zoraptera) is described with the main focus on its external features. A small heart-shaped embryo is formed on the dorsal side of the egg by the fusion of paired blastoderm regions with higher cellular density. The orientation of its anteroposterior axis is opposed to that of the egg. This unusual condition shows the potential autapomorphy of Zoraptera. The embryo extends along the egg surface and after reaching its full length, it migrates into the yolk. After developing there for a period of time, it reappears on the surface, accompanied by a reversion of its anteroposterior axis, finally taking its position on the ventral side of the egg. The definitive dorsal closure completes, and the prelarva hatches after perforating the chorion with very long egg tooth formed on the embryonic cuticle. Embryological data suggest the placement of Zoraptera among the "lower neopteran" or polyneopteran lineage: features supporting this are embryo formation by the fusion of paired regions with higher cellular density and blastokinesis accompanied by full elongation of the embryo on the egg surface. The extraordinarily long egg tooth has potential synapomorphy with Embioptera or Eukinolabia (= Embioptera + Phasmatodea). Together with the results from our previous studies on the egg structure, male reproductive system and spermatozoa, the close affinity of Zoraptera with Eukinolabia appears likely, that is, a clade Zoraptera + (Embioptera + Phasmatodea).

Trichorionic and dichorionic triplet pregnancies at 10-14 weeks: outcome after embryo reduction compared to expectant management.

OBJECTIVE: To compare the outcome of trichorionic triplet (TCT) and dichorionic triplet (DCT) pregnancies managed expectantly and those with embryo reduction (ER) at 10-14 weeks to twins or singletons. METHODS: This was a retrospective study of triplet pregnancies with 3 live fetuses managed expectantly or by ER. Data were combined with the results of previous studies that used similar entry criteria and outcome measures. The management options were compared for rates of miscarriage and preterm birth <33 weeks. RESULTS: In TCTs managed expectantly (n = 358), the rates of miscarriage and preterm birth were 3.1 and 35.1%. Compared to the expectantly managed TCTs, the rate of miscarriage was higher and preterm birth lower in TCTs with ER to 2 fetuses (n = 833, 7.3 and 13.1%, respectively) and TCTs with ER to 1 fetus (n = 78, 11.5 and 8.7%). In DCTs managed expectantly (n = 136), the rates of miscarriage and preterm birth were 8.8 and 46.0%. In DCTs with ER to 2 fetuses (n = 15) or ER to 1 fetus (n = 42), there was a non-significant increase in miscarriage (13.3 and 16.7%, respectively) and decrease in preterm birth (23.1 and 8%, respectively). CONCLUSIONS: In TCT and DCT pregnancies, ER increases the rate of miscarriage but reduces the rate of preterm birth.

The volume of the chorion villosum is associated with the location of the umbilical cord in the first trimester.

AIMS: To clarify whether villous placental volumes in cases with low cord insertion (CI) are smaller than those with normal cord insertion. METHODS: A prospective cohort study was conducted to evaluate the association between location of umbilical CI and placental volume at 11 to 13 weeks' gestation. An ultrasound examination was performed to measure the crown-rump length, the distance between the histological internal cervical os and the CI site, the placental volume, and the uterine arterial blood flow. To standardize the distribution of the ultrasonographic measurements, we transformed data by crown-rump length-weighted linear regression. RESULTS: Six hundred fifty-nine subjects were analyzed. Scatter plots showed a slightly positive correlation between the z-scores of the distance from the CI site to the internal cervical os and villous placental volume (r = 0.102, p = 0.009) and a negative correlation between the z-scores of the villous placental volume and the uterine arterial pulsatility index (r = -0.165, p < 0.001) as well as the uterine arterial resistance index (r = -0.187, p < 0.001). CONCLUSION: The placental volume was likely to be smaller in cases with CI located in the lower uterine segment.

Dichorionic pregnancy: delayed interval delivery with endoloop ligation.

We describe two cases of delayed delivery in dichorionic, diamniotic pregnancies, where we used an Endoloop ligature to clamp the umbilical cord with excellent maternal and fetal long-term outcome.

Prospective risk of stillbirth: monochorionic diamniotic twins vs. dichorionic twins.

AIMS: To determine reliably the risk of stillbirth among twin pregnancies. METHODS: A data analysis of 3241 and 6581 women with monochorionic diamniotic (MD) and dichorionic (DD) twins, respectively, who gave birth at ≥22 weeks of gestation. RESULTS: The prospective risk (per 1000 women) of stillbirth, 25.3 and 11.5 at gestational week 22, decreased to <10.0 at gestational weeks 31 and 28 among the MD and DD twins, respectively. After single intrauterine fetal death, the co-twin died in utero or within 7 days of life more frequently among MD twins than among DD twins [42.7% (35/82) vs. 2.6% (2/76); relative risk, 16.2; 95% confidence interval, 4.0-65.1]. CONCLUSION: Women with MD twins were 2.2-fold more likely to experience stillbirth than women with DD twins. The prospective risks of stillbirth were <1.0% for both groups of women at ≥32 weeks of gestation.

Perinatal mortality and morbidity in twin pregnancies: the relation between chorionicity and gestational age at birth.

AIM: To investigate perinatal mortality and morbidity rates of twin pregnancies and to determine the underlying factors responsible for the increase in these rates. METHODS: Records of 300 twin pregnancies which have been followed in our clinic between 1996 and 2005 were reviewed retrospectively. Perinatal mortality and morbidity rates, zygocity, chorionicity, gestational age at delivery, route of conception, birth weight, route of delivery, fetal gender and cesarean rates were investigated. RESULTS: A total of 16,549 deliveries have been reviewed and 2.9% (n = 484) of these were detected to be twin deliveries. Perinatal mortality, adjusted perinatal mortality, fetal loss, neonatal mortality and perinatal morbidity rates were 7.5, 6.9, 3, 5.8 and 15.4%, respectively. The principal causes of perinatal mortality were prematurity, fetal demise and congenital abnormalities. The main cause of morbidity was respiratory distress syndrome (RDS). In neonatal period 28% of newborns needed neonatal intensive care unit (NICU) and 12.1% received positive pressured ventilation (PPV). Perinatal mortality and morbidity rates were found to be independent from zygocity, instead they were closely linked with chorionicity. Perinatal mortality and morbidity were higher if maternal age was under 18 and over 35, and were not effected by intrauterine growth retardation (IUGR), discordance between twins or RDS prophylaxis. CONCLUSION: Twin pregnancies have higher perinatal mortality and morbidity rates and potential obstetrical complications compared to singleton pregnancies, therefore should be monitored more intensely, appropriate precautions should be taken against obstetrical complications, especially before 31-32 weeks of gestation, deliveries should be performed in referral centers with competent NICUs.

Quantification of free fetal DNA in multiple pregnancies and relationship with chorionicity.

OBJECTIVE: Free fetal DNA (ffDNA) in the maternal plasma appears to originate mainly from the trophoblast. We tested the hypothesis that ffDNA concentration is increased in multiple pregnancies where trophoblastic mass has been shown to be increased. METHODS: Quantitative real-time PCR was used to measure the plasma concentration of DYS14 in singleton and twin pregnancies with one or two male fetuses. Royston and Wright's regression method was used to relate ffDNA to gestational age in singleton controls; z-scores were calculated for the multiple pregnancy subgroups. RESULTS: Fifty-five singleton and 65 twin pregnancies (36 with one and 29 with two male fetuses) were analysed. There was significantly higher ffDNA concentration in twin pregnancies with two male fetuses compared with pregnancies with one male fetus. In cases with two male fetuses, there was no statistically significant difference between monochorionic and dichorionic pregnancies. CONCLUSIONS: There is higher ffDNA concentration in multiple pregnancies, and this must be taken into account for future quantitative ffDNA applications.

Progressive chorion morphology during egg development in Samia ricini (Donovan).

The egg of Samia ricini (Donovan), is oval or laterally flattened ellipsoid, freshly laid eggs are candid white while the chorion is colorless and semi-transparent. The surface of the chorion is covered with network patterns of polygons and their shapes are common in the whole surface region. The boundaries between polygons made ridges had distinct acropyles at three-cell junctions. The numbers of aeropyles are variable according to their structures both in the lateral flat and marginal regions. During the course of egg development, no significant structural changes were observed in either the polygonal structures or the overall morphology of the egg. However, the size of the aeropyles kept on changing as the egg matures. The aeropyle increases initially upto day-9 of egg development and then decreases as it approach hatching. Lines of weaknesses were not observed at time of hatching or close to it. Hatching process of the newly emerge larvae are through gnawing. The larva eats their way out through the chorion membrane mostly from the anterior region. Egg buster or spine which aid in hatching are not present in the newly emerge larvae.This article was published online on 25 September 2009. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected 6 January 2010.